Klassenkameraden (1984)

The criminalist Hannes Bergemann tries to blackmail the city where he spent his youth. After many years returning to the familiar places of his childhood, he hopes to meet again his old friends, especially Fred, Helmuth and Richard, with whom he had a close childhood friendship. When confronted with a murder shortly after his arrival and given the task of investigating it, he has the painful experience that his friends are involved in the case.

Unfortunately the movie Klassenkameraden is not yet available on HBO Max.