Simon encounters drama in a bus shelter. It involves sudden death, sabotage and a very beautiful girl.
An American airman is seeking revenge against The Saint and starts by putting a 5,000-pound bounty on his head.
Poppaea plans to poison Barbara who has become the object of Nero's affections. The Doctor is to be thrown to the lions, Ian and Delos are set against each other in the arena.
Barbara is sold as a slave and Ian is to be trained as a gladiator.
Inspired by the Doctor, Nero sets Rome ablaze. Ian must fight his way out of the arena and rescue Barbara. The Doctor and Vicki hurry to flee the city and escape to the TARDIS.