Dog Eat Dog! (1964)

Original title: Einer Frisst den Anderen

Two killers, a deadly blonde and a million stolen dollars spell death on a lonely, lust-ridden island.

Three thieves rip off a shipment of used money being sent back to the US. As they are escaping the robbery (after having taken a hostage), they wind up on an island in a hotel with an apparently crazed manager and a building full of demented residents.