On the surface, there's nothing unusual about the Hursts' home life: Director Alan Rudolph ("The Moderns," "Trixie") captures the comforting, messy normalcy of their daily routine: the dinner time cacophony, the morning breakfast rush, or, most remarkable of all, a long, sustained sequence in which the household is infected by a flu bug, with one member of the family recovering just as another falls ill.

But after catching a fleeting glimpse of Dana kissing another man, David begins to doubt everything he's taken for granted. Suddenly, every call Dana makes to say she'll be home late is rife with suspicion, every word she utters loaded with meaning ("I wish we were closer sometimes," she tells him one night in bed, and he feigns sleep in order to not have to respond.)

David isn't even entirely sure he saw what he thinks he saw, but he can't bring himself to confront his wife, fearing that once the subject is broached, it can only lead to divorce. "The Secret Lives of Dentists" is about David's insecurity and paralysis, about a man who, having grown comfortable in his marriage and now faced with the unthinkable, can't bring himself to act on it, even though it consumes his every waking thought.

The movie is at its best when Rudolph allows Scott ("Roger Dodger") and Davis ("About Schmidt") — two underrated, exacting actors — to burrow into the darker corners of a marriage whose participants may have started to take each other a little too much for granted. Rudolph being Rudolph, however, the movie injects an unwelcome element of surrealism in the form of one of David's patients (played by Denis Leary) who becomes a personification of his repressed id, sitting alongside him as he argues with his wife, riding with him in his car, constantly needling him to deal with the situation head-on, something David seems incapable of doing.

Leary's presence quickly grows tiresome, and "The Secret Lives of Dentists" would have been a better movie without him. But Scott and Davis keep you interested in the Hursts' dilemma as a couple wondering when the flame in their romance blew out, and whether or not there's any hope of rekindling it.