The Doctor talks to Ambril and Chela to try and stop the 500th anniversary celebrations. A possessed Tegan finds herself in Dugdale's Hall of Mirrors to where she summons Lon. The Doctor and Nyssa return to the caves.
| Name | Type | Role | |
|---|---|---|---|
| Chris Bailey | Writer | ||
| Martin Clunes | Guest Star | ||
| Jonathon Morris | Guest Star | ||
| Hilary Sesta | Guest Star | ||
| John Carson | Guest Star | ||
| Colette O'Neil | Guest Star | ||
| Fiona Cumming | Director |