With the Ark infected with a cold virus, the Doctor must convince the Guardians to trust him so he can find a cure.
| Name | Type | Role | |
|---|---|---|---|
| Paul Erickson | Writer | ||
| Stephanie Heeson | Guest Star | ||
| Frank George | Guest Star | ||
| Ian Frost | Guest Star | ||
| Inigo Jackson | Guest Star | ||
| Edmund Coulter | Guest Star | ||
| Eric Elliot | Guest Star | ||
| Paul Greenhalgh | Guest Star | ||
| Kate Newman | Guest Star | ||
| Michael Imison | Director |