Adrien Brody hallucinates while straitjacketed into a box. You’re at the same risk watching this film.

When director John Maybury set out to unravel this time-travel tale, he aimed for an ambitious mixture of melodrama, romance, realism and sci-fi. That’s a high target, and he falls far short. What could have been a mind-bending psycho-thriller comes out no better than a mediocre episode of “The Twilight Zone” (albeit with Adrien Brody).

The Oscar-winning Brody plays Jack Starks, a Gulf war veteran suffering from amnesia after being shot in the head. A year later, trudging along a wintry Vermont road, he stumbles on drug addict Jean (Kelly Lynch) and her vivacious daughter, Jackie (newcomer Laura Marano). After this chance meeting, Jack suffers from an amnesia-inducing blackout and awakens in a courtroom accused of murder. He remembers little of the crime, but the strong evidence against him condemns him to an asylum under the sinister eye of caretaker Dr. Becker (Kris Kristofferson). While there, Jack undergoes an inhuman form of therapy involving a straitjacket, syringes and confinement in a coffin-like drawer.

In the darkness of his confinement, Jack is haunted by flashbacks of his army years, but he soon realizes that, with considerable control, he’s able to “flash forward” to a future where he’s free. The year is 2007 and he meets a troubled girl in the form of a grown-up Jackie (Keira Knightley). The two fall in love and with four days till his death (don’t ask), the movie turns into a ridiculous race-against-time goose chase with the pair trying to discover the reason for Jack’s impending death. Along the way, he gains the support of Becker’s colleague, Dr. Lorenson (a brilliant and underused Jennifer Jason Leigh).

The most memorable thing about “The Jacket” is the tremendous amount of potential left unrealized. Three-quarters through the movie, impatience sets in as the film descends into nonsense. The only worthwhile scenes center on Brody and Leigh’s intense chemistry. And (spoiler): there’s absolutely no mystery unraveled at the end of the film. Instead, the only real head-scratcher is why you didn’t walk out earlier.