Brothers Jerry Lee (Stephen Dorff), left, and Frank (Emile Hirsch) watch out for each other — through good times and bad — in “The Motel Life.” (Polsky Films)

Alan and Gabe Polsky are brothers, which may explain why “The Motel Life,” their first foray into directing, is such an affecting piece of filmmaking. The movie, based on the novel by Willy Vlautin, delves into the relationship of another set of brothers as they throw up a united front against an assault of bad luck.

Jerry Lee (Stephen Dorff) and Frank (Emile Hirsch) haven’t had it easy. Their father left when they were young, and their mom died when they were teenagers. Not long after, Jerry Lee lost a leg while trying to jump on a moving train. But at least the two have always had each other. In a flashback, we see the pair’s mom, as her health declines, telling her boys the authorities might try to split them up, and she orders them not to let that happen. All these years later, it’s clear there was never any danger of that. The two are inseparable and completely devoted to one another, even when Jerry Lee makes a string of horrible decisions.

One night, he kills a boy while driving, but rather than call the cops, he drops the body off near a hospital then sets fire to his car. Much of the movie deals with whether the men should stay put in Reno or flee to another town.

The idea of escape is also the theme of a subplot about Frank’s incredible storytelling abilities. Growing up, he would usher Jerry Lee and himself into another world where they had heroic escapades and romantic dalliances. Frank still tends to spin a good yarn, and when he does, the movie breaks into dazzling black-and-white animation by Mike Smith.

Hirsch and Dorff do a tremendous job playing the alcoholic caretaker and the hapless ne’er-do-well, respectively. Dorff looks the part of the gaunt and prematurely aged Jerry Lee, and he captures his character’s slow unraveling. Frank isn’t one to talk about his feelings, so when Hirsch is shown driving around aimlessly with an expressionless face and a single tear rolling down his cheek, the result is heartbreaking.

Yet, for all its melancholy and grey, snowy landscape, “The Motel Life” never feels totally hopeless, thanks in large part to colorful ancillary characters (not to mention occasional trips into Frank’s mind). Dakota Fanning shows up in a bittersweet subplot as Frank’s former love interest, and Noah Harpster plays one of the brothers’ unhinged buddies who has cautionary tales about a recent trip to “the loony bin.” Meanwhile, Kris Kristoffersen has a memorable bit role as a father figure who offers sage, if crude, advice.

These characters make the film feel more approachable, as does Jerry Lee and Frank’s relationship. Sure, they’ve experienced more bleak episodes than many people, but this isn’t just a tale of woe. It’s about the incredible bond of two siblings, who can’t help but want to make things right.

★ ★ ★

R. At West End Cinema. Contains language, nudity, sexual situations, brief violent images and drug references. 85 minutes.