An Amtrak train is a terrible place to shoot dope. My seat mate tells me this after the train jerks, causing his syringe to slip from his vein. I take his word for it.

Jarek Camac and I are on our way to Los Angeles. For Jarek, a decorated Army combat veteran, it's a trip meant to both figuratively and literally deliver him from addiction to sobriety, from his old life of using in Delaware to a clean life in California.

For me, it's a revealing and ultimately heartbreaking trip borne out of "No Man Left Behind," a story I worked on for VICE on HBO that airs tonight. In it, we look at the many Iraq and Afghanistan veterans who have graduated from morphine to painkillers to heroin, and the systemic failures within the Department of Veterans Affairs (VA) that have led them to do so.

"Kansas City, next stop!" the conductor announces just outside our private room.

Jarek, having finally gotten his fix, nods off.

* * *

I'd met him a week earlier outside his apartment in suburban Delaware. It was his 27th birthday, and he was dead broke — but that wasn't a big problem. The local dealers all knew he was good for the cash, because each month the government deposited a disability payment of almost $4,000 into Jarek's bank account. As he liked to joke, he was PTSD: Paid Till Suicide or Death.

Jarek spent 30 months in Afghanistan between 2006 and 2009 as an infantryman with the 10th Mountain Division. On his final deployment, Jarek was injured; the military gave him narcotics for the pain. After returning home, Jarek fell into the grip of an opiate dependency. He had subsequently bounced in and out of VA hospitals for years, trying and failing to get clean.

"I've just gotta stop shooting dope and start dealing with problems instead of getting high and not thinking about them," he tells me. "It's gotta be better somewhere else, so I guess I'm trying to find somewhere else."

"The doctors will be like, 'No, you need help for your addiction, that's your main problem.' Well, that's being caused by other things."

The Amtrak trip to LA is a three-night journey that stops in Washington, DC before heading northwest through Chicago and then on to California. I accompany Jarek with a camera for VICE on HBO. He loves it.

During the day, the train's lounge car is filled with professionals, vacationing families, and casual travelers gazing out of oversized windows at the passing landscape. As the sun sets and the bar opens, a different tone settles over the car. By the middle of the night, while others sleep, the addicts and insomniacs find each other here. Jarek is clearly at home.

"What do you hope to do in Los Angeles?" asks one woman who admits she's recovering from a drug dependency after Jarek tells her about his. "There's more drugs there than anywhere else."

Jarek takes a drag from his e-cigarette and blows out slowly.

"I need to fix my head," he tells her. "The doctors will be like, 'No, you need help for your addiction, that's your main problem.' Well, that's being caused by other things. If you don't fix the things behind the addiction you're just going to get out and keep using over and over and over again."

* * *

Attempting to solve problems with painkillers is what's done throughout the VA health system.

An analysis last year by the Center for Investigative Reporting found that since 2001, the number of major narcotic painkillers prescribed to veterans has increased 270 percent, a rate that dwarfs the concurrent rise in the number of patients. As part of our investigation, VICE spoke with whistleblower Pamela Gray, who testified before Congress about the dangerous levels of narcotics she witnessed being prescribed while working as a doctor in a VA hospital.

Instead of helping, the VA is actually creating addicts, she tells us. "Narcotics are very cheap. You can see high volumes of patients in a short amount of time at relatively no cost."

For veterans suffering from mental health issues like PTSD and anxiety, narcotics such as OxyContin and Vicodin actually increase the risk of depression and suicide. A major study of Iraq and Afghanistan veterans found that the VA contributes directly to these problems by prescribing such high levels of opiates.

As Gray says, "I do not understand how any medical institution in good conscience can perpetuate a therapy that is harmful to the people that they are supposed to serve."

* * *

The final morning of our journey, Jarek wakes up and watches the sun rise, illuminating the LA skyline. We've made it, but we have several hours to kill before Jarek is due to head to the VA, so I take him to the beach.

We sit on the sand together and watch surfers. It's the perfect ending to a cross-country trip, I think. But Jarek is unusually quiet.

"What are you thinking about?" I ask.

"Honestly, I can't stop thinking about heroin," he says, looking down at his phone. "I'm googling where to buy heroin in Los Angeles."

Jarek on the beach in LA, sizing up the Pacific Ocean

He's been sober for almost a day, having blown through his supply of dope and pills on the train. The withdrawal symptoms — cold sweats, vomiting, diarrhea — have started to kick in.

When we get back to our rental car, Jarek tries shooting up the dusty residue from empty baggies. He's getting desperate, so I turn the ignition of the car and start driving toward the hospital.

I film Jarek as he walks into the emergency room. He goes to the front desk and says his rehearsed line, 10 words he knows all too well: "I am a threat to myself, and I need help."

A nurse then escorts Jarek down a long hallway and out of sight. Once again, he has put his life in the hands of the VA.

* * *

I hear from Jarek occasionally over the next year. The LA experiment ends up being short-lived, as Jarek quickly finds himself in the same frustrating system he thought he'd left behind on the East Coast. He begins using again.

Then in October of 2013, an Army buddy in San Diego offers Jarek a place to stay provided he stays clean. Living with a friend from combat in a supportive family environment, Jarek finds himself on the right track for the first time in a long while. He completes a three-month in-patient rehab program at the local VA and begins studying for an Information Technology degree with the University of Phoenix. It's what he's been hoping to do since before he joined the Army.

But the hunger is still there. When what turns into his final benefit check hits his account in February, Jarek buys a train ticket East. It's for his brother's bachelor party, he explains.

His Army buddy drives him to the train station and watches as Jarek boards. He waves goodbye. "See you next Saturday," Jarek tells him.

Forty-eight hours later, Jarek's body is found in the bathroom of a train station outside LA, a needle still stuck in his arm. In his wallet is an Amtrak ticket to Delaware.

"It's hard because it's like using drugs has been what has brought me happiness for the last four or five years," Jarek had told me as we pulled into LA the year before. "That pretty much exclusively is what I've done to be happy, and I don't know, it's hard to give that up without something solid to replace it."