The Antarctic, the near future. A strange seed-pod is unearthed from 20-thousand-year-old ice. The Doctor and Sarah go to investigate, but are too late to prevent the pod infecting a scientist and unleashing a threat to all animal life on Earth...
| Name | Type | Role | |
|---|---|---|---|
| Robert Banks Stewart | Writer | ||
| John Gleeson | Guest Star | ||
| John Challis | Guest Star | ||
| Mark Jones | Guest Star | ||
| Tony Beckley | Guest Star | ||
| Seymour Green | Guest Star | ||
| Michael Barrington | Guest Star | ||
| Michael McStay | Guest Star | ||
| Kenneth Gilbert | Guest Star | ||
| Hubert Rees | Guest Star | ||
| Douglas Camfield | Director |