De rijke advocaat Martens wordt vlak na half elf 's avonds vermoord. De politie treft ter plaatse de jonge Peter Hartman. Alles wijst op zijn schuld, maar de inspecteur neemt geen genoegen met de voor de hand liggende oplossing van roofmoord

Painter Peter Hartman is arrested at the scene of a murder. He soon turns out to have ties to the victim's young widow. As Inspector Stroomer begins to unravel the mystery, two very different sides of the story are presented to him. Now it is up to Stroomer to find enough photographic evidence to make out which version is the truth.