On the planet, there was land, and on the land, there were cities, and in a city, there was a park, and in the park, there was a lake, and in the lake, there was a swan. One swan among many. Cygnus olor, a mute swan, three years old, in good health.

The swan did not have a name for himself, because wild birds don't. He was the swan who lived in the best place on the lake, the fiercest fighter, the strongest flier, and that was all he needed to identify himself to any bird.

And there was a human (Homo sapiens, early forties, good health, easy temperament, grey colouring) who liked the swan. He did have a name, Greg Lestrade, because there are so many humans they need such things. He was a keeper at the zoo in the park, where it was his job to care for captive birds (and where many of the birds cared for him in return, especially Molly, the griffon vulture [Gyps fulvus], a beautiful female near his own age who loved him for providing her with interesting carrion but was too shy to press her suit across species lines). He called the swan Roadblock.

The swan was willful and beautiful even for a swan, he thought. The arch of his neck had swagger. He could and did take on any bird, person, boat, bicyclist, or car in the park. "What a pain in the arse you are," Lestrade said to the swan fondly. The swan ignored him and continued watching the road, searching for the source of bread. (The swan reasoned that humans were the providers of bread, but not the source of bread, because he had investigated everything bread-colored on all the humans he could find [the small blond girl was not, in fact, traumatized, but regaled friends with the story of the swan that ate her hair for the rest of her life] and it did not come from them per se; therefore, the swan concluded, bread was something that they carried, like ducks carried nesting material or magpies carried shiny things, and could be found someplace else if he went and looked. Every time he ventured outside the park, though, he was chased back in, and once even trapped in a sack, which was intolerable.)

There was also a duck in the lake, one duck among many. The duck (Gadwall duck, Anas strepera, fully adult but smallish) was gray-brown with black and white patches on his backside and belly, nothing compared to the more colourful denizens of the lake. Even Greg didn't notice him at first. The duck ate his share of tourist breadcrumbs and generally did all right in the lake.

Lestrade finally noticed the duck the second time he saw him grazing near the swan. "Pushing your luck there, Johnny," he said to the duck, leaning on his elbows on the footbridge. "You're going to get your feathers plucked." (He generally called unfamiliar males Johnny and unfamiliar females Rosie. He was unaware that this was because those were the names of the sheepdogs his great-grandfather kept, but he would not have been surprised if he found out. He inherited his love of animal work from that man.)

But the swan didn't attack the duck, even when the duck surfaced and flicked water into the swan's face. The swan just shook his head and swam closer.

"Huh," Lestrade said, and after that, he noticed the duck, tagging him as Roadblock's little pal. (He could easily tell the duck apart from other ducks. He was a professional. He had trouble with people sometimes, because they changed their clothes and their hair, but birds were perfectly individual to him.)

The swan and the duck were together most of the time. They slept side by side on the island at night. The swan never chased the duck away, because the swan knew what Lestrade did not: the duck had saved his life, snatching a fishing hook out of the swan's beak before the swan could swallow. The swan was reckless about these things. The duck was older and knew what was not food.

The park was an excellent place to live for all manner of creatures, humans included. The swan disliked most humans, despite the fact that they brought bread and chips, because they were bright and loud and behaved like the territory was theirs instead of his. He made the papers after beating a man named Anderson (aged thirty-eight, possessed of a very loud, annoying phone) in the face, giving the man two black eyes and a broken nose and breaking his phone. The swan was lucky his species was protected.

The swan calmed down a bit after meeting the duck. The duck didn't give a toss about territory, only sun and food and good sleeping spots, and his appreciation of simple comforts was a lesson for the swan.

The swan did strut a bit more, though, showing off his neck while the duck watched him from the water. Pictures of the swan appeared on a great many local Facebook walls. Lestrade found this hilarious.

"You know that's a duck, don't you?" he asked the swan one evening. The swan touched his bill to the duck's. "A male duck, you mad wanker," Lestrade said, grinning. "He has a meter-long corkscrew penis. It'll never work."

The swan, of course, ignored him (and would have ignored him even if he understood. He had chosen his life companion. Mute swans are faithful once committed). Lestrade amused himself on the train ride home picturing beak jobs and webbed foot frottage. His wife Sophie asked him what was so funny and he said, "Gay swan" and kissed her.

The swan still investigated the bread question. He hopped up onto a bridge to peer into the nest of the two local magpies, spreading his wings to keep his balance. "Nheck," the duck said, watching him. The swan grunted in reply. He leaned over to look at the shiny things the magpies kept in the nest--and fell headfirst back into the water (swans are large birds and do not fly without a good run-up. The swan didn't fly so often as he propelled himself across the water with his wings like a motorboat). The swan righted himself swiftly and the duck swam over to straighten the swan's feathers. "Nheck," the duck said. He nibbled softly at the swan's breast. The swan shook his wings into place and curved his neck into an elegant S shape.

(The magpies, Pica pica, male and female, had names of a sort; Lestrade, seeing the male sorting aluminium cans from the trash, marked black and white not unlike a suit and tie, called him the Public Servant. On a later occasion, watching the male and female work in concert to untangle silver tinsel from a bush, he called the female the Personal Assistant. The prize of the collection of shiny things was an iPod Touch which the magpies could probably have used, were it not out of charge. The magpies were fond of the swan because the humans dropped all manner of shiny things when the swan chased them.)

Late one night, a young thief ran through the park. He saw coppers behind him; he saw coppers ahead of him. He would inevitably be caught, but he was crafty, and he'd heard of some old tricks. He swam across to the island and looked around at the sleeping fowl. The swan, ever curious, ever eager to defend his territory, raised his head, and their eyes locked.

The boy seized the swan by the throat and stuffed his loot into his mouth. By the time the swan unfolded his wings fully, preparing to give the boy a good beating, the boy was swimming back to shore, plotting how best to come back and kill the swan to retrieve his sapphire.

The boy roused the magpies as he ran. They cawed loudly and harassed him. When he swatted at the birds, the police spotted him and took him into custody.

The swan was extremely cross in the morning. His crop was full, but not with food. He hissed irritably at the pair of police officers searching the lakeside. (They caught the thief soaked to the skin; suspicious, evocative, but they needed proof, and they hoped to find a stash on the islands. They searched the magpies' nest thoroughly, with the magpies cursing and fuming at them as their precious iPod was confiscated, but neither of them thought to look inside a bird, because neither of them had read as many Victorian detective novels as the boy.)

The swan charged a coot. He charged a boxer dog. He charged Lestrade for looking at him too long. "For fuck's sake!" Lestrade yelped, dropping his breakfast scone. "What's got into you?" The duck grabbed the scone. He'd been hovering around the swan, made fretful by his stroppiness, but he wasn't one to ignore a nice fresh pastry.

The swan settled down once Lestrade backed away. He nibbled at the scone (the duck still munching along, a brace of pigeons looking for an opening) but his throat hurt when he tried to swallow. He hissed at Lestrade once more for good measure.

Lestrade rang the Regents Park bird keeper once he arrived at work. His assistant, Donovan, answered. "Roadblock is poorly," he said.

She knew which swan he meant, though she called the swan "that tosser" instead. "How long?"

"Just today. He looks like he has something in his crop."

She sighed. "He's probably eaten something daft. It might pass. I'll keep an eye on him and see how he's doing tomorrow. I don't want to try to catch him if he's just had some off biscuits. Mrs. Hudson likes to handle the swans herself and she's not as young as she used to be." (Mrs. Hudson was the head keeper, well respected by all the birds in the park.)

"Yeah, fair enough," Lestrade said. But it worried him all day. The park just wouldn't be the same without the swan.

The swan didn't eat all day. The duck swam close to him, butting his head against the swan's breast, but he didn't know how to help. That night, the swan roosted in his usual spot, the duck beside him, but both slept badly.

The young thief (fourteen years of age, history of animal cruelty, history of schoolyard violence, accomplished purse-snatcher and pickpocket, three prior burglaries, never caught by the authorities) returned to the park the following day. He had been stopped by police but released. They knew he'd done it, of course, but there was no proof. He was feeling damned cocky. He just needed to find the right fucking swan.

He guessed wrong once. He buried the body in a shrubbery and cursed swans for all looking the fucking same. He was a clever boy, though, Jim Moriarty, and he put on his best schoolboy face and sat on the park bench to learn the swans.

He got lucky and saw Lestrade. Lestrade, with bird shit on his shoes, hay in his turn-ups, and scratches on his forearm from a friendly parrot (Tobias, a rainbow lorikeet [Trichoglossus haematodus], who gamboled over Lestrade's body like playground furniture). He followed Lestrade's gaze and found the swan, floating listlessly in the middle of the lake.

Moriarty waited.

The swan was aching badly that night. The duck sat beside him, head under the swan's wing. They were both awake when Moriarty found the swan, which is what saved the swan's life.

Moriarty lassoed the swan with a length of cord, fancying himself a cowboy. He tightened the cord and let the swan try to escape, let him strangle himself. The swan beat his wings weakly. He understood birds and dogs and trees and grass, but he didn't understand ropes. He thought it might be a branch caught on his neck and if he flapped hard enough, it would drop off, but he was weak from hunger and exhaustion.

Moriarty would have killed him, but for the duck. The duck flew up in his face, pecked him, and beat him with his wings. Moriarty screeched and dropped the cord, which released the tension on the swan's neck. The swan lurched backwards, panting for breath.

The duck bit Moriarty on the nose and blood spurted down both their fronts. Moriarty grabbed the duck by the wing and foot and panted through his mouth as the duck struggled. He hadn't realized the bird could hurt him back, and it made him furious.

He let go of the duck's foot, grabbed its wing in both hands, and snapped the bone. He tried for the duck's neck next, but the duck flopped away from him as soon as he adjusted his grip. He paused; he was bleeding freely from his nose. He needed to get the swan before--

The magpies roused and cawed, waking half the sleeping flock. The birds muttered and rustled on the island.

"Oi! Who's out there?"

Before someone saw him, out on the island, where no human was allowed to be. Moriarty looked for the swan, thinking he could grab the cord, but the swan had run off. He didn't notice the duck at his feet. He cursed and jumped into the water to dog-paddle back to the shore.

The swan staggered in a circle back to the duck. They huddled together and grunted to each other in distress.

The bird keeper's assistant, who had seen Moriarty, rowed up to the island in her boat. She shone her torch across the sleeping birds and caught the splash of blood on the duck. She sighed, thinking the duck had been killed by a fox, but then the swan raised his head into the light and the duck moved.

The assistant took them both in and rang the police. "Someone tried to poach a swan," she said. She didn't mention the duck, but kept both birds comfortable until morning, when Mike Stamford (brown and rosy colouration, plump, the avian vet at London Zoo) could take a look.

Stamford set the duck's wing. "Poor Johnny," Lestrade murmured, holding the duck in his hands as it came out of anesthesia. "He's going to lose that wing, isn't he?"

"Probably. Fragile bones. But I'll give it my best go," Stamford said. "Handsome little fellow, isn't he?"

"Bold as brass, snuggling up to that mad swan." Lestrade smoothed the feathers on the duck's breast.

Then Stamford removed the sapphire necklace from the swan's crop, where it was tangled among the grit the swan used to grind his food. He handled it carefully, which was fortunate, because Jim Moriarty's partial fingerprint was able to be retrieved from the finding (he was young and careless with his gloves, a mistake he never made again).

The newspaper headline read: The Swan Detective. A misnomer, as the swan was the crime scene rather than the detective, and it was the duck who had the greater role in apprehending the burglar, but a wounded duck wasn't nearly as photogenic as a swan with a bandaged throat. (The magpies tore a photograph of the shiny blue sapphire out of a magazine. They recognized the photograph of the swan and looked at him suspiciously, wondering at his proximity to the prize. "Keck," the male magpie muttered. "Quok," the female replied, tucking the sapphire under the shiny new Blackberry they had stolen from one of the police.)

Lestrade guessed, though, and Donovan guessed, and the swan knew, and while the duck did lose his left wing, he quickly grew fat as a lord. During the day, the swan paraded up and down the pavement, collecting accolades and biscuits, and the duck sloped along in his shadow, eating the best bits. At night, the duck tucked his wounded side against the swan's down, and the swan made contented little grunts to know he was there, beside him, under the stars.

the end.