Chaney plays two roles: mad scientist Arthur Lamb and Lamb's "experiment", known only as the Ape Man. This hideous creature was the result of Lamb's attempts to transplant animal glands into human beings. A lost film.
| Actor | Role |
|---|---|
 Lon ChaneyDr. Arthur Lamb / The Ape Man | Dr. Arthur Lamb / The Ape Man |
 Raymond McKeeRobert Sandell | Robert Sandell |
 Jacqueline LoganAngela Marshall | Angela Marshall |
 Virginia True BoardmanMrs. Sandell | Mrs. Sandell |
 Fontaine La RueMrs. Lamb | Mrs. Lamb |
 Aggie HerringBessie | Bessie |
| VVirginia MadisonAngela's Mother | Angela's Mother |
 Wallace BeeryBeast Man (uncredited) | Beast Man (uncredited) |