While watching for a planet that may collide with earth, scientists stationed in Scotland are approached by a visitor from outer space.
| Actor | Role |
|---|---|
 Robert ClarkeJohn Lawrence | John Lawrence |
 Margaret FieldEnid Elliot | Enid Elliot |
 Raymond BondProf. Elliot | Prof. Elliot |
 William SchallertDr. Mears | Dr. Mears |
| RRoy EngelTommy the Constable | Tommy the Constable |
| DDavid OrmontInspector Porter | Inspector Porter |
| GGilbert FallmanDr. Robert Blane | Dr. Robert Blane |
| PPat GoldinThe Man from Planet X | The Man from Planet X |
| TTom DalyDonal, a searcher | Donal, a searcher |
| JJune JefferyWife of Missing Man | Wife of Missing Man |