Directing
| James P. Hogan | Director |
Cast
| Ralph Bellamy | as Ellery Queen | |
| Margaret Lindsay | as Nikki Porter | |
| Charley Grapewin | as Insp. Queen | |
| Mona Barrie | as Nurse Marian Tracy | |
| Paul Hurst | as Page | |
| James Burke | as Sgt. Velie | |
| Leon Ames | as John Stack | |
| George Zucco | as Dr. Edwin L. Jannery | |
| Blanche Yurka | as Mrs. Augusta Stack | |
| Charlotte Wynters | as Miss Fox | |
| Tom Dugan | as Lou Thomas | |
| Olin Howland | as Dr. Williams (as Olin Howlin) | |
| Dennis Moore | as Dr. Dunn | |
| Jean Fenwick | as Alice Stack | |
| Pierre Watkin | as Crothers |

