An earlier one of the classic German Edgar Wallace films, Der Rächer does not yet try to reach the effect of fright too often by showing screeaming women or pointing out frightening moments by zooming onto dead bodies and having us hear earsplitting, shrieking sounds. It is a solid mystery story, with a plot that is almost logical and can be followed rather easily. (The idea of course reminded me of the hilarious Arsenic and Old Lace, but this was a completely different thing. I guess, Edgar Wallace wrote his novel earlier, and maybe Joseph Kesslering read it, maybe he didn't.)
Heinz Drache plays the detective, Ingrid van Bergen plays, in one of her rare Wallace appearances, the beautiful girl that needs to be protected. Klaus Kinski is a sinister character on the verge between genius and madness. So there is nothing new concerning the cast (only Eddi Arent is missing, but I didn't really miss him), no world-shattering surprises, except maybe at the end. Good Sunday-afternoon suspense.