A serviceable if shopworn mob drama set in 1973 New York City, “Brooklyn Banker” features a powerful lead performance by Troy Garity as an honest man who gets mixed up in nasty doings.

Garity, showing flashes of his grandfather Henry Fonda’s stone-faced decency (his parents are Jane Fonda and Tom Hayden), plays Santo, a bank officer with a gift for numbers who’s asked by the local mob boss (David Proval) to verify some cashier’s checks. The checks are OK, but Santo’s father-in-law (Paul Sorvino) tells him to say they’re bad, which leads to ruthless recriminations against an innocent person.

Borrowing a few tricks from Martin Scorsese, the film isn’t a slavish imitation but an engrossing and grounded drama. It’s a pity, then, that director Federico Castelluccio, best known as Furio of “The Sopranos,” can’t deliver a powerful conclusion.