Perry loses a case at the beginning of this episode. Actually, it's a civil case involving a patent dispute and he lost because the opposition led the jury to believe that Perry paid a witness to change his testimony. How did this happen? A merchant seaman named Grimes was paid to impersonate Perry and passed an envelope to a key witness. Grimes, it seems, is a dead ringer for Mason. The civil case soon turns into a criminal one when the winning party in the patent dispute is murdered. (thetvdb.com)