An alien intelligence hitches a ride onboard the TARDIS to 15th century Italy, where a deranged astrologer attempts to harness its power.
| Directing | Rodney Bennett | Director |
| Writing | Louis Marks | Writer |
| Production | Philip Hinchcliffe | Producer |
| Writing | Robert Holmes | Script Editor |
| Sound | Dudley Simpson | Original Music Composer |
| Costume & Make-Up | James Acheson | Costume Design |
| Camera | John Baker | Camera Operator |
| Lighting | Dennis Channon | Lighting Director |
| Costume & Make-Up | Jan Harrison Shell | Makeup Artist |
| Editing | Clare Douglas | Editor |
| Sound | Hugh Cleverley | Sound |
| Sound | Colin Dixon | Sound |
| Crew | Dick Mills | Special Sound Effects |
| Art | Barry Newbury | Production Design |
| Production | Thea Murray | Production Assistant |
| Visual Effects | Ian Scoones | Visual Effects Designer |
