The Doctor and Peri have been rescued from the firing squad by the mysterious Sharaz Jek. But he has his own plans for them. And why are they suddenly feeling ill?
| Name | Type | Role | |
|---|---|---|---|
| Robert Holmes | Writer | ||
| Roy Holder | Guest Star | ||
| Christopher Gable | Guest Star | ||
| Robert Glenister | Guest Star | ||
| Maurice Roëves | Guest Star | ||
| Barbara Kinghorn | Guest Star | ||
| Martin Cochrane | Guest Star | ||
| David Neal | Guest Star | ||
| Graeme Harper | Director |