Source: Mad Love aka The Hands of Orlac
Here is a brief review of a long-forgotten Peter Lorre movie that sounds very interesting based upon critiques of the time and the modern-day reviews. I will probably be seeking this one out.
The reviewer’s concise description of the plot is at the best inadequate. He doesn’t mention what relation Stephen Orlac is to Yvonne Orlac (brother? husband?) and he doesn’t even allude to what Orlac does with his new-found ability with knives, though I suppose we are to guess that he uses them against Dr. Gogol in some fashion. He probably could have done better.