A Fejenincs Írástudó (1980)

The Chief Officer found dead on a morning in his well isolated room, doors locked from inside, armed guards outside at the door. The inspector find it weird, as seemingly no one was there when he stabbed in his heart. Turns out soon he has a wife, who is kept in a cage. The inspector want to meet her, and she says she actually not the wife of the Chief Officer, but she came to the palace with her husband who was killed by the CO.