Blake tries to rescue the remaining prisoners from the prison planet Cygnus Alpha only to find they have a disease that can be cured by the power mad high priest Vargas
| Name | Type | Role | |
|---|---|---|---|
| Terry Nation | Writer | ||
| Peter Childs | Guest Star | ||
| Glyn Owen | Guest Star | ||
| David Ryall | Guest Star | ||
| Norman Tipton | Guest Star | ||
| Pamela Salem | Guest Star | ||
| Robert Russell | Guest Star | ||
| Brian Blessed | Guest Star | ||
| Vere Lorrimer | Director |