Professor Samuel Hale Constable is a government expert in the field of cybernetics. He and his wheelchair-bound wife Lenore became parents late in life, only to lose their daughter Mary before she reached adolescence. Now their daughter's spirit seems to be reaching out to her grief-stricken father from beyond the grave, encouraging him to give up the important project on which he's been working.
| Actor | Role |
|---|---|
 Don MurrayDr. Alex Lauder | Dr. Alex Lauder |
 Ray MillandProf. Samuel Hale Constable | Prof. Samuel Hale Constable |
 Gene TierneyLenore Constable | Lenore Constable |
| BBarbara DanaTina Cryder | Tina Cryder |
 Ed AsnerSaul Wiener | Saul Wiener |
 Pamelyn FerdinMary Constable | Mary Constable |
 William BeckleyArnold Watson Bessmer | Arnold Watson Bessmer |
 Ivor BarryDr. Paul Cryder | Dr. Paul Cryder |
 George MacreadyDr. Frank Ferguson | Dr. Frank Ferguson |
 John CarradineMr. Bosch | Mr. Bosch |
 Virginia ChristineHelga | Helga |
| CCecile OzorioDevi Bessmer | Devi Bessmer |
 Frank MaxwellGeneral Augstadt | General Augstadt |
 Hal FrederickC.I.C. Technician | C.I.C. Technician |
 Bill HickmanEnemy Agent | Enemy Agent |