Sometimes a serviceable story is elevated by casting. In “Hope Springs,” it’s two casting masterstrokes.

The story concerns a husband and wife whose 30 years of togetherness has curdled into a deadening routine. Arnold is a grumpy accounting executive whose day revolves around not interacting with his wife, Kay. She wistfully wishes to recapture the marriage they once had, but being a timid soul, she hardly knows where to begin the salvage process. They attend counseling, talk about their issues and begin rebuilding.

So far, so what. Except that the no-longer-happy couple is played by Meryl Streep and Tommy Lee Jones in wonderfully committed performances.

Now we’re talking.

Directed by David Frankel (“The Devil Wears Prada”), the film deals knowingly with the details of a marriage that has drifted into tedious routine.

They live like two recluses under the same pleasant middle-class roof. There are no fireworks. Each is studiously polite and determined to avoid friction.

Streep can steal a look at Jones and make her eyes whimper. Jones, politely keeping his wife at emotional arm’s length, distills his trademark irascibility to the essence of discomfort.

The film is naturalistic and low-key. Much of it follows their trip from Omaha to Maine for a week of intensive counseling.

Steve Carell plays it utterly straight as the celebrity therapist who assists them in renewing their commitment. The film’s best scenes are top-drawer actors speaking unremarkable lines while extracting every drop of meaning from them.

Jones rankles at Carell’s assignment to talk about his feelings and fantasies — his evasive replies and ill-at-ease body language are eloquent far beyond his plainspoken dialogue. Streep portrays a mild-mannered, nondescript frump, and does it brilliantly.

The counseling episodes have a smattering of laughs, but they’re presented as serious business.

The film is a dual character study aimed at getting couples to open up and talk to each other.