An alien vessel manages to break the earth defense systems. Captain Layton is sent to investigate and find the invaders. Together with friends from the planet Ganymed he discovers the enemies in a hidden underground city on earth.
| Actor | Role |
|---|---|
 John RichardsonCaptain Mike Layton | Captain Mike Layton |
 Yanti SomerDiane Greene | Diane Greene |
 Walter MaestosiIrk | Irk |
| GGaetano BalestrieriColonel Dawson | Colonel Dawson |
 Gisela HahnDr. Helen Parker | Dr. Helen Parker |
 Aldo CantiFrank Bimble | Frank Bimble |
 Massimo BonettiLt. Vassilov | Lt. Vassilov |
 West BuchananCaptain Connolly | Captain Connolly |
 Lucio RosatoProfessor Burton | Professor Burton |
 Malisa LongoReplicant | Replicant |
 Giuseppe FortisHerman Wesson | Herman Wesson |
 Omero CapannaNot listed | Not listed |
| RRomeo CostantiniNot listed | Not listed |
| Giuseppe FortisNot listed | Not listed |
| DDaniele DublinoNot listed | Not listed |
 Vassili KarisNot listed | Not listed |