When the Silurian leader is killed, all hopes of peace are lost. The Silurians infect Major Baker with a virus deadly to humans and release him to spread the infection.
| Name | Type | Role | |
|---|---|---|---|
| Malcolm Hulke | Writer | ||
| John Churchill | Guest Star | ||
| Paul Barton | Guest Star | ||
| Nigel Johns | Guest Star | ||
| Harry Swift | Guest Star | ||
| Geoffrey Palmer | Guest Star | ||
| Timothy Combe | Director |