Oom Henk.

Handsome, clever final year law student Koen avoids being beaten up by street thugs by claiming he's a maternal cousin of crime baron Henk de Koning. The next day, 'uncle' Henk praises Koen's wit and commandeers his 'cousin's' help to retrieve the treasure presumably hidden by disloyal accomplice Sjon de Nooyer, who was released from jail to a retirement home, by volunteering as an orderly, posing as Sjon's distant relative. Dirty police detective Uitenhaage is after the same fortune, and leans independently on innocent Koen to spy on Sjon.