|157a||27x01||"The Stolen TARDIS"||
Shadow City, 1996
|Cassandra 'Cass' O'Brien||The Shadow Lords||First appearance of Cassandra O'Brien (Charley Webb). First appearnace of The Shadow Lords.|
|157b||27x02||"The Stolen TARDIS"||
Shadow City, 1996
|Cassandra 'Cass' O'Brien||The Shadow Lords|
|158a||27x03||"Nightmare on Vicar's Street"||Vicar's Street, London, 1888||Cassandra 'Cass' O'Brien||The Nightmare Man||First appearance of The Nightmare Man|
|158b||27x04||"Cassandra's Curse"||Vicar's Street, London, 1888||Cassandra 'Cass' O'Brien||The Nightmare Man|
|159a||27x05||"The Sisterhood"||France, 1643||Cassandra 'Cass' O'Brien||The Cult of Sisters||First appearance of The Cult of Sisters|
|159b||27x06||"The Sisters of Blood"||France, 1643||Cassandra 'Cass' O'Brien||The Cult of Sisters|
|160a||27x07||"The Last Battle"||Gallifrey||Cassandra 'Cass' O'Brien||The Daleks||
Reappearance of The Daleks
Reappearance of The Time Lords
|160b||27x08||"The Time War"||Gallifrey||Cassandra 'Cass' O'Brien||The Daleks||Final appearance of Cass O'Brien|
Paul McGann returned as The Doctor. Charley Webb debuted as Cass O'Brien, who was killed off in 'The Time War' after being exterminated by a Dalek during the war.
The Shadow Lords debuted in episode 157. The Nightmare Man debuted in episode 158, played by Leslie Grantham. In episode 159, the Cult of Sisters debuted. Francesca was played by Maisie Williams, Leanna by Catherine Tyldesley and Shardanay by Sophie Austin.
The Time Lords and Daleks re-appeared in episode 160. Nicholas Briggs returned to voice the robotic monsters.
Gallifrey returned in episode 157, before returning back to Gallifrey in episode 160. After the Time War, the Doctor was forced to destroy Gallifrey. London returned in episode 157, at two periods in time - 1997 (present day) and 2057 (the future).
Shadow City - a secret underground city situated under the Earth - made its first appearance in episode 157. In episode 158, the Doctor visited Vicar Street in 1888, a dream-state street on the planet Nightfall, which was controlled by the Nightmare Man. The doctor travelled to France, 1643, in episode 159, where he was attacked by The Cult of Sisters, the leader of which, Shardanay, was actually being controlled by an alien vampire bug which was slowly killing her.
These episodes are currently being written.