Last Monday evening, 7.15pm. The southbound Dart train’s emergency brakes screech and scream for several deafening, terrifying seconds until it halts abruptly. Then silence. No crash. We’re still alive, is my first thought. Hundreds of homebound commuters on the packed train have had their routine disturbed. They look out the windows.

“There’s a naked man on the tracks,” a woman says. People raise their iPhones to take pictures of the tanned body with the wizened face running past the window. Some laugh and joke. Most ignore him and go back to their digital devices and books for distraction. This is an annoyance, nothing more. Let’s hope it doesn’t last too long.

The naked man disappears. For several minutes we don’t know what’s going on. Next the driver announces that there is a naked man lying on the tracks in front of the train, preventing us from moving. We have been stuck between Blackrock and Seapoint stations for 10 minutes. The naked man emerges again along the side of the train like a freakish sideshow. A female commuter comments that he must be enjoying the attention.

“If there is any security on the train, please come to the driver’s cabin,” comes the announcement. Burly men in black do not appear.

Eventually the train begins to move again in slow fits and starts, then stops at Seapoint station. The doors open and remain open, giving access to the platform and giving the weary passengers much-needed fresh air. The naked man runs past the open doors. He is losing his novelty for the commuters, mostly workers, on a hot evening when they want to get home to enjoy the last of the good weather.

As he runs back and forth, I catch his eye and see the fear in his face. He is terrified. A young woman in dark trousers and a pink jacket leaves the train to talk to him. He is very agitated. She tries to hold his attention. Her body language is confident but she is having difficulty keeping him from moving past her to jump on to the tracks again.

The driver has given the naked man an orange hi-vis vest to wear. It barely covers what it’s meant to. It’s comical to some of the commuters and provides another photo opportunity.

****

I leave the train and approach the man. “What’s your name? Why are you doing this?”

He fixates on me.

“What’s your name?” I ask again.

He latches on to my gaze and tells me his name. Let’s say it’s Joe.

“Joe, why are you doing this?”

“They’re after me. The train; it wants to kill me.”

His language and his story are confused, as he speaks about enemies that only he can see. “No guards, no guards.” He tries to jump up on a metal bench and over the wall. He is bleeding.

“What happened?” Joe says that he fell off a 30-foot wall on to the tracks and lost his clothes.

“Lost them where? Were you sunbathing?”

“Yeah,” he says, before insisting that he was not attempting to take his own life.

When he tries to run again, the young woman grabs his arm in a professional manner. He doesn’t like this. He threatens to jump again.

“Joe, are you on drugs?” I ask.

“No. They’re after me. I don’t want the guards. The guards will kill me.”

The young woman says calmly and with authority, “I’m sure you know some guards. They’ll take you to hospital. You’re bleeding. You need to be looked after.”

The driver is standing firm on the other side of the young woman, the three of us corralling him. The driver tells me the naked man was lying on the tracks. He’s lucky to be alive, and the driver is shaken. His heart “won’t stop beating fast”, he tells me.

The gardaí are taking ages to arrive. The young woman whispers, “I’m a garda, but he can’t know that.”

The off-duty garda keeps trying to ring the nearest Garda stations, but they don’t answer. For 30 minutes there is no response from them. We hear sirens, but they’re not for us. The siren sounds agitate Joe further and he talks insensibly about the terrible things they are going to do to him.

“I’m on my way to a party and now I’m late. Really late,” the young woman says. She has to go home and change, and then head back into town.

I ask Joe where he lives, whether he has a family, and whether I can phone anyone for him. Like the off-duty garda, I stand close enough to him to keep him from running but not so close as to threaten him.

I don’t let his gaze leave mine. He keeps looking to me for reassurance.

“You’re going to be okay, Joe,” I say, wishing I could believe it.

“When they come for me, will you come with me?” he asks me, like a child. He says he is 53. He looks older. Has a gold stud in his left ear.

“Tell me about your tattoos.” The question seems to ground him a little. He looks over his body and shows off a tattoo on one arm with his daughter’s name, and a tattoo on his chest with an ex-girlfriend’s name. Joe seems utterly unselfconscious about standing almost naked on a train platform dressed only in an orange high-vis vest.

“Have you been in hospital? Do you need to be back in hospital?” I ask.

“Yes,” he says, to both.

“The gardaí will take you to hospital,” the young woman says.

I tell him that I am a journalist and ask him to tell me his story. I ring the newsdesk at The Irish Times and give him my phone to speak to a reporter. Joe seems eased by this acknowledgement that his story is important. He tells his story and it calms him down.

A tall, thin man emerges from the train and walks slowly towards Joe, as one might approach a scared wild animal. He says gently: “You know me, Joe. I know you. I’m a nurse.” He names the psychiatric hospitals where he has worked. I can see the hospital ID tag around his neck. “Look at all these people who want to go home. Why don’t you come for a walk with me, and let them go home,” the nurse says gently.

“No,” says the off-duty garda.

The naked man turns away from the nurse, who withdraws, and tries to climb on to a bench to jump over the wall. The off-duty garda grabs his arm to stop him.

Joe becomes more agitated and wants to run along the tracks to Dún Laoghaire. He wants only to go home.

A man, an insurance salesman, gets off the train and stands by the end of the platform so he can stop the man before he attempts to jump back on to the tracks.

Finally, the gardaí arrive, walking confidently at a slow pace down the platform. The train doors start to beep. It starts up again as the gardaí approach Joe. They are much bigger than him, and he goes peacefully.

The train doors start to beep indicating that it’s about to leave. I jump back on to the train, and a few seconds later the young garda just makes it through the doors .”I was terrified the train was going to leave before they got here and I was going to be alone with him. I’m late for my party,” she says again.

“He really wanted to tell his story. I think it calmed him down,” I say.

“I was going to kill you at first,” she says.

“You’re a great social worker. That training in Templemore must be pretty good.”

She smiles.

We chat our way back to normalcy for a couple of stops.

I disembark at my station and walk home. I’m unable to sleep wondering what has happened to Joe. There is a news report about the disrupted Dart services. But there is one disrupted life that I can’t forget.

*****

Three days later, I am on my way to work when Joe gets on the Dart and sits beside me. He’s delighted to see me and is in much better form. He’s wearing a shiny green and orange Adidas tracksuit, and new fluorescent orange and green runners.

“You’re looking well. Much better,” I say.

I notice a few stares as I sit with him and he blurts out his story. He says he was trying to kill himself on Monday. This is the opposite of what he had said to me and the off-duty garda that evening.

“Why?”

“I was psychotic. It was the drugs. I thought the train was going to kill me. It wasn’t even a train. This voice in my head. Telling me that I had a choice. I could go out and attack a paedophile, or else kill myself.”

“What was the drug?”

It was snowblow, he says: the crack cocaine of the moment, and in many ways worse because you never know what’s in it, he explains.

“I was going to kill anyone who touched me.” I remember the off-duty garda gripping his arm and how he reacted. How she didn’t touch him again. Joe says he knew she was a garda all along.

Joe’s story flows out, more cogently than last time. He is homeless. He is living in an abandoned house in Dún Laoghaire. He can’t use hostels because he’s afraid to be in a room with other people: not for his own safety, but for theirs, he says.

He tells me he has just got out of prison in the past few days. His brother died an hour after he got out. He couldn’t attend his brother’s funeral because he wasn’t able to go to the church. He can’t go anywhere near a church. His family has fractured, with his wife and daughter living with his brother, who is his daughter’s “stepfather”. He says that before Monday’s incident he had been clean of drugs for two years: “even methadone, and that’s the hardest to come off”. That was in prison. So having been detoxed, the snowblow hit him hard.

“Where did the gardaí take you?”

To the garda station, where they locked him up, he tells me. “I was alone and the demons were all around me I could see them dancing on the walls. I don’t know how long I was in there; it felt like days. I wanted to be sectioned [put in a locked ward in a psychiatric unit] but they wouldn’t listen.

“Then I heard the bastard who gave me the snowblow in the next cell and that made it worse.” He says he is angry at the drug dealer for “playing a trick” on him with such a strong drug.

When the gardaí let him go, he left the station. Later he went to the dlr LexIcon, the new library in Dún Laoghaire that cost €36.6 million, and sat on the steps. The man who sold him the drug came and sat beside him. Joe thinks this man should be “sliced up”; he suggests this has already happened but it wasn’t him who did it. “People think I did it but I didn’t.” He says there was a fight on Dún Laoghaire pier, where the dealer was attacked. It’s impossible to know whether to believe any of this.

Joe says he was put into an industrial school at the age of 12. “I’ve been in prison ever since,” he says. He started heroin at 16 and has been in and out of prison for theft to pay for drugs.

He mentions The General, Martin Cahill.

He talks about the Commission to Inquire Into Child Abuse.

Joe seems unaware of the other commuters eavesdropping on our conversation. He rants about paedophiles and “Brothers”. He says he was sexually abused and that the drugs were meant to kill the pain, but they didn’t. He says he sees the demons who abused him all day and all night, and can’t get them out of his head.

The other commuters have kept their faces turned, and ignore Joe and I as we disembark at Tara Street station.

Joe says he feels that his life was destroyed in childhood, and that the decades since have been about killing the pain.

As we go down the stairs, there are several security people waiting at the gates and scanning the passengers getting off the trains. Joe puts his ticket in the machine. It doesn’t work, so he goes through the security point and is passed through.

We shake hands. He thanks me for listening to his story. “Please write it. I want everyone to know. I want my brother to know. There’s a book in me.”

Joe heads off to get his social welfare payment. After that he plans to go to Merchants’ Quay Ireland homeless and drugs service, where he will get food.

“Will you do drugs today?” No, he answers, limping severely. It looks as if he was injured in the fall and hasn’t been treated.

“See you, and thank you,” he says, as he is absorbed into city homelessness and I head to work in my shiny office.

I expect I shall meet him again on the Dart some day.