Department S (1969)

S1E10 The Treasure of the Costa del Sol

In the sunny Costa del Sol, Spain, on July 31st, a man enjoys a scuba diving adventure while his friend remains in the car. Upon surfacing, the diver proudly brings back a fish, but his friend unexpectedly shoots him. Despite his injuries, the diver manages to retaliate with a spear gun, fatally wounding the shooter. A passing policeman arrives at the chaotic scene and discovers that the diver's catch is not what it seems—inside the fish is a hidden stash of $100,000 in cash.