From The Perry Mason TV Show Book (Revised)
Perry Mason suborning perjury? Never! Except this once, sort of. This episode is a rare bird indeed, and the only time you’ll see double when you see Burr. Raymond Burr appears in his regular role as Perry, and also plays Mr. Grimes, a drunk, a troublemaker, and the spitting image of Perry Mason. The “Mr. Grimes” role is a lot closer to the characters Burr was used to playing before he came to the Mason series.

Perry finds himself on the losing end of a patent dispute case when his opposition leads the jury to believe that Mason paid a witness to change his testimony. How could this have happened? A cockney merchant seaman named Grimes is a dead ringer for the noted attorney. With a little makeup and some coaching, Grimes merely impersonated Perry and passed an envelope full of money to a key witness.

The civil case turns into a criminal one when the winning party in the patent dispute is murdered. The number one suspect is Perry’s client, Barbara Kramer, but the lawyer thinks the murderer may be someone a lot closer to home.