The Adventure of Sherlock Holmes’ Smarter Brother (1975)

Director: Gene Wilder
Cast: Dom DeLuise, Douglas Wilmer, Gene Wilder, John Le Mesurier, Leo McKern, Madeline Kahn, Marty Feldman, Roy Kinnear

Synopsis:

After spending decades living in the shadow of his more famous and successful sibling, Consulting Detective Sigerson Holmes (Wilder) is called upon to help solve a crucial case that leads him on a hilarious trail of false identities, stolen documents, secret codes… and exposed backsides.