1976 film by Duccio Tessari

A quirky, but happily in love young Italian couple fall in with an older, but distinctly reserved Swedish couple whilst on vacation on islands off the coast of Southern Italy. Eventually the couples seem to warm to each other as the infectious youths bring the standoffish couple out of their shells. But there is a sinister reason for the Swedish couple's cold behavior and it may spell doom for them all.

A number of unexplained military deaths hit Italy and are ruled to be accidental or suicides, but police inspector Giorgio Solmi suspects otherwise. When a mysterious wealthy electrician is seemingly murdered by a female escort, a sinister plot slowly begins to unravel.