The Invisible Ray

Dr. Janos Rukh discovers a certain type of radium that has almost magical healing properties. But the element has a dangerous side, too, and it has already started affecting Rukh. Consumed by paranoia, he begins to suspect that his wife is having an affair. Wild for revenge, Rukh hatches a deadly plot...using his own poisoned body as a weapon to kill.

• 
  Lambert Hillyer

• 
  Boris Karloff
  Dr. Janos Rukh
• 
  Bela Lugosi
  Dr. Felix Benet
• 
  Frank Lawton
  Ronald Drake
• 
  Frances Drake
  Diana Rukh
• 
  Violet Kemble Cooper
  Mother Rukh
• 
  Beulah Bondi
  Lady Arabella Stevens
• 
  Walter Kingsford
  Sir Francis Stevens
• 
  Paul Weigel
  Monsieur Noyer
• 
  Frank Reicher
  Professor Meiklejohn
• 
  Georges Renavent
  Chief of the Surete
• 
  May Beatty
  Mme. LeGrand (uncredited)
• 
  Paul McAllister
  Papa LaCosta (uncredited)
• 
  Nydia Westman
  Briggs (uncredited)
• 
  Ynez Seabury
  Celeste (uncredited)
• 
  Robert Graves
  Gendarme (uncredited)