Zero Effect (1998)

Private investigator Daryl Zero (Bill Pullman) is one of the finest sleuths in the world but also one of the most eccentric. A recluse prone to odd behavior, Daryl utilizes his assistant, Steve Arlo (Ben Stiller), as his face to see clients. When businessman Gregory Stark (Ryan O'Neal) falls victim to a blackmail plot, he employs Daryl to find the culprit. Daryl starts to home in on Gloria Sullivan (Kim Dickens) as a suspect, but he also finds her attractive, which complicates the case.