The Mad Doctor of Market Street

Lionel Atwill

Dr. Ralph Benson, posing as Graham

Una Merkel

Aunt Margaret Wentworth

Nat Pendleton

Red Hogan

Claire Dodd

Patricia Wentworth

Anne Nagel

Mrs. William Saunders

Hardie Albright

William Saunders

Richard Davies

Jim

John Eldredge

Dwight, Ship's Officer