Daryl Zero, as one of the film's slogans goes, is "the world's most private detective." His unbending procedures include refusing ever to meet his clients. He's outrageously expensive, and he never negotiates his fee. His methods are unorthodox, but he's so good, he's sometimes able to solve his cases without leaving his high-security Los Angeles apartment. Daryl is represented by his full-time associate, a lawyer named Steve Arlo (Ben Stiller), whose attitude toward his boss vacillates from awe to contempt. Steve serves as Daryl's field assistant and liaison with clients. He's a pretty smart guy himself, but he never does figure out what Daryl is up to.

Daryl's current job is The Case of the Missing Keys. Oregon timber tycoon Gregory Stark (Ryan O'Neal) has lost his keys to a safety deposit box, the contents of which he refuses to divulge. Meanwhile, in a development that may or may not be related, Stark is being blackmailed on charges of having raped a woman many years ago when he was a Harvard undergraduate. He doesn't know the identity of his blackmailer. Intrigued, Daryl agrees to accept the case and even, reluctantly, to leave his apartment. Soon, employing a variety of disguises and techniques, Daryl is ferreting out the relevant details of Stark's life and current dilemma. "My work relies on two basic principles," Daryl says, "objectivity and observation, or the two 'obs,' as I call them." In The Case of the Missing Keys, however, Daryl's objectivity gets clouded by an unprecedented development: he falls for the woman, Gloria Sullivan (Kim Dickens), who just might be the blackmailer.

In Zero Effect, Daryl Zero (Bill Pullman, left) and Steve Arlo (Ben Stiller) reprise a familiar entertaining partnership.

A lesser writer would have turned this material into a sequel for The Naked Gun or The Pink Panther. But filmmaker Kasdan makes no use of physical comedy and never goes for the cheap laugh. As a result, Zero Effect offers a freshness we seldom get from a mainstream Hollywood feature, even one like this with a narrow release strategy. And yet, in significant regard, Daryl Zero is actually a canny modernization of that king of sleuths himself, Sherlock Holmes. Kasdan never strives to point up this comparison, but it's notable that like Holmes, Daryl has a trusty assistant, Watson become Arlo, doctor become lawyer. Both detectives are able to deduce huge patterns of behavior from seemingly insignificant physical details. And also like Holmes, Daryl has a troubled private life. Holmes is a melancholic coke-head; Daryl is an agoraphobic neurotic.