Editor's Note, December 10, 2013: With the second chapter of The Hobbit trilogy opening in theaters soon, and the third and final film to be released next winter, refresh your memory about what happened in the first film.

For readers of The Hobbit, which became an almost overnight classic following its 1937 debut, the new movie may elicit some puzzlement. Seemingly extraneous flourishes clog up what many remember as a simple fairy tale, and random characters appear at every twist and turn throughout Middle Earth.

Yet those fans who went on to immerse themselves in J.R.R. Tolkien’s wider lore will find inspiration. For the most part, director Peter Jackson does not exercise an extra heaping of artistic license. Rather, Jackson—reportedly something of a nerd himself—borrows from the larger Tolkien literature to create a rich Hobbit tableau.

“Jackson knows the lore pretty well and wanted to bring that larger material in there wherever he could,” said Michael Drout, an English professor at Wheaton College who founded the academic journal Tolkien Studies and edited the J.R.R. Tolkien Encyclopedia. It’s this so-called textuality—or texts behind texts behind other texts—that lends Tolkien’s work the air of reality, he said, and which Jackson seeks to capture in his films.

Jackson isn’t free to tap into any detail he wants from Tolkien’s wider works, however. “He had a very difficult task in that the movie rights extend only to The Hobbit and Lord of the Rings,” said John Rateliff, an independent Tolkien scholar and author of The History of the Hobbit. “He’s well aware that there’s a great deal more material set in that world, but contractually not allowed to use that material in the movies.”

More information about some of the plot threads from The Hobbit movie appear in Unfinished Tales (published posthumously by Tolkien’s son, Christopher, in 1980), for example, and The Silmarillion (also published posthumously, in 1977), but Jackson can only hint at the content of these rich texts.

Throughout the film, Jackson tiptoes around this problem, alluding to the larger Tolkien universe when he can. For instance, the mysterious blue wizards, who Gandalf briefly mentions to Bilbo in the movie, are identified by name only in Unfinished Tales, hence Gandalf conveniently “forgetting their names” to spare Jackson a potential lawsuit.

Similarly, while Hugo Weaving’s elf lord of Rivendell, Elrond, recognizes that one of the swords recovered from the troll cave hails back to the goblin wars and once belonged to the king of Gondolin, an Elven city that fell to darkness, he fails to mention the king’s name, Turgon, and does not add that Turgon is actually his own great-grandfather. These details come from The Silmarillion and The Book of Lost Tales (published posthumously, in 1983 and 1984). “Elrond could have quite easily have said, ‘Hey, thanks for bringing that back, we wondered what came of that sword over the last 7,000 years,’ but he doesn’t,” Rateliff said.

At one point, Jackson edges dangerously close to the fine line of intellectual rights. “The Quest of Erebor,” a story contained in Unfinished Tales, retells the opening chapter of The Hobbit from Gandalf’s point of view. In it, Gandalf justifies his uncanny attraction to Bilbo, a hobbit with “a love of tales” and “eagerness in his bright eyes.” In the film, Gandalf chidingly asks when Bilbo became more interested in china and doilies than in adventure, mirroring those lines from Unfinished Tales. “I wonder if the Tolkien estate will sue over it,” Drout said. “They are litigious.”

Some of the other references are easy to spot, like Frodo’s appearance at the beginning of the The Hobbit harkening back to The Fellowship of the Ring. Others are more cryptic, however. With Jackson's obfuscation about where the many threads came from, it would be easy for even the mild Tolkien fanatic to get confused. Recognizing some of these twists may help dubious fans be more supportive of Bilbo’s tri-installment cinematic journey—and also appreciate Jackson’s own celebrated nerdery.

(See the full-version infographic of where these plot points came from)

Azog the Orc

The big bad from the first movie, for example, is only briefly mentioned in The Hobbit, but more devoted readers recognized this scene from Appendix A of The Lord of the Rings (the appendices are found at the end of The Return of the King, the third book in the trilogy): a battle between orc and dwarf raged at the east gate of Moria. The dwarf prince Thorin, grandson of the King Under the Mountain, received a mighty blow, cleaving his shield in two. Taking up a protective oak branch in its stead, Thorin began pummeling his foes, earning him the moniker Thorin Oakenshield.

Still, Jackson doesn’t get it exactly right. This business of Thorin amputating the arm of Azog, the albino orc king, for example, is poppycock so far as the books are concerned. According to Tolkien, Azog first brutally murders Thorin’s grandfather in a one-on-one encounter, and there’s no arm amputating or all-consuming vendetta following the dwarf-verus-orc showdown—which Azog does not survive. “I was calling Azog “Mobi-Orc,” like a cross between Moby Dick and Captain Ahab,” Drout said of his reaction while watching The Hobbit. “He’s got the missing limb and is after his enemy like Ahab is after the whale.”

Dol Guldur and the Darkness

One of The Hobbit’s more mysterious characters was the Necromancer, described only as a dark sorcerer of unknown origins.

Elrond describes “a time of watchful peace” after the first fall of Sauron and the taking of the One Ring, depicted in the battle with Isildur in the Fellowship of the Ring movie. But a darkness may be gathering at Dol Guldur, “the hill of sorcery” in Mirkwood forest where the Necromancer reportedly takes up shop. Radagast confirms these rumors by producing the Witch King's sword. These details (save the sword—that’s a Hollywood addition) mostly took place offstage in Tolkien’s The Hobbit, but Jackson weaves them into his version.

One other discrepancy exists, however: in Tolkien’s books, Mirkwood forest fell to darkness about 2,000 years before Bilbo’s journey, but for dramatic effect Jackson moved those events up to present day. Unlike the map depicted in The Hobbit (the book), Thorin’s version in the movie reads “Greenwood the Great” in place of “Mirkwood,” demonstrating Jackson’s attention to detail.

The White Council

In the Hobbit movie, Elrond and company form a White Council, where Gandalf urges his powerful colleagues to take action against the growing darkness in Mirkwood but wizard Saruman the White shoots him down (not yet turned evil as he is in the earlier film trilogy, but he’s starting to think about it). All of these details are covered in the Lord of the Rings and its appendices, though the Council’s discussions and decision to take action against the Necromancer occur over a period of 490 years in the series.

“At heart, Jackson and his team did a careful job of scouring The Hobbit and The Lord of the Rings for more information about events at the time of Bilbo’s journey,” Rateliff said. “They made good use of these to flesh out events that occur off-stage in Tolkien’s original book, like the meeting of the White Council.”

Radagast the Brown

In the movie, Bilbo and the dwarves face imminent death by an approaching orc horde in the western lands of Eriador (not 100 percent clear since this meeting never took place in the books), when the wizard Radagast the Brown turns up with his sled of rabbits to save the day. Though a Jackson addition, this scene does pay homage to Tolkien with two much-appreciated nerd references. First, Gandalf warns that his friend cannot outrun the wolf-like Wargs, since they are from Gundobad. This seemingly made-up label actually refers to Mount Gundobad, the goblin kingdom to the north of Mirkwood forest. Radagast is not having it, however. “These are Rhosgobel rabbits, I’d like to see them try!” he retorts, making a second reference to his equally obscure homestead of Rhosgobel.

Radagast himself appears only briefly in The Lord of the Rings and The Hobbit when Gandalf mentions his existence. Radagast’s central role in the film—especially the rabbit chase scene, which made Drout wonder “if George Lucas was allowed to touch the script”—is Jackson’s invention.

(See the full-version infographic of where these plot points came from)

Ungoliant the spider

Even Ungoliant, an evil spirit who originated “before the world” and takes the form of a massive spider, gets a brief citation. “Ungoliant is mentioned in The Lord of the Rings in the description of Shelob, ‘last child of Ungoliant,’” Drout said. “But you’d only know the significance of the word Ungoliant if you’d read The Silmarillion.”

Potential plot threads for the next films

Having a handle on the Tolkien lore can also clue fans in on potential scenes to come in the second and third Hobbit movies. (Warning: for those who prefer to avoid possible spoilers, skip this section!) For example: Will viewers be treated to a flashback of Gandalf wandering into the dungeon of Dol Guldur to recover the map and key for the Lonely Mountain from Thorin’s crazed, imprisoned father, Thráin? Will Galadriel’s forces take on the Necromancer as detailed in the appendices and hinted at in The Hobbit when she reassures Gandalf, “If you need me, call and I will come?” And will Bilbo meet an intriguing 10-year-old named Aragorn in Rivendell on his journey back to Hobbiton?

Of course, some fans will never be satisfied by Hollywood’s stab at Tolkien, no matter how faithful the films are to the original works. When technology reaches the point that Tolkien zealots can produce their own movies, however, this may change. “Some nerdy person like I was when I was 14 will sit in a basement for three years and come out with a film that perfectly renders everything,” Drout predicted. “At that point, there will be nothing that intellectual property lawyers can do to stop it.”