Ostensibly, "Pearly Gates" (Peter Sellers) is a French couturier selling posh frocks, but we know in reality he's a crook. Imagine his chagrin when his latest crime falls foul of the police! Imagine how much worse it gets when he discovers that it wasn't the police at all, but a gang who "IPO" (Impersonate Police Officers). That's below the belt! Meantime, the rather supercilious police inspector "Parker" (Lionel Jeffries) starts to get embroiled in this too as his bosses don't much like the idea that there are fake officers out there robbing with impunity. The most unlikely of truces now…