The Cat Burglar(1961)

Unwitting pickup artist Jack Coley (Jack Hogan) nabs a briefcase holding a costly scientific formula, turning himself into a moving target for owner Alan Sheridan (John Baer), foreign agents and the fuzz -- all bent on a blistering game of finders, keepers. In this stylized crime drama, the quarry coolly eludes the pack while eliciting the aid of an unlikely party: blonde beauty Nan Baker (June Kenney), the attaché's original carrier.