The Doctor and Martha follow a trail of clues across alien worlds to find the location of the Infinite, a legendary lost spaceship.
| Name | Type | Role | |
|---|---|---|---|
| Alan Barnes | Writer | ||
| Toby Longworth | Guest Star | Caw / Squawk | |
| Steve Meo | Guest Star | Pilot Kelvin | |
| Liza Tarbuck | Guest Star | Captain Kaliko | |
| Barney Harwood | Guest Star | Control | |
| Tom Farrelly | Guest Star | Swabb | |
| Stephen Greif | Guest Star | Gurney | |
| Lizzie Hopley | Guest Star | Mantasphid Queen | |
| Dan Morgan | Guest Star | Locke / Warders | |
| Anthony Head | Guest Star | Baltazar | |
| Paul Clayton | Guest Star | Mergrass | |
| Gary Russell | Director |