After a bad TARDIS landing, The Doctor, IAN, Barbara, and Vicki are living in an unoccupied Roman villa during the reign of Emperor Nero. The Doctor goes off the explore Rome with Vicki, but Ian and Barbara are seized by slavers. Ian is sold to one slave-owner, Barbara to another.
On route to Rome, the Doctor and Vicki find the murdered body of a lyre-player. A Centurion finds The Doctor holding a lyre and takes him to Rome as the lyre-player, who was supposed to be assassinated. The Doctor overpowers the assassin and the Centurion runs away, so the Doctor decides to impersonate the lyre-player in Rome.
Barbara is handmaiden to Nero’s second wife, the Empress Poppaea (Kay Patrick). When the Doctor and Vicki arrive at the court of Nero (Derek Francis), they discover that the lyre-player was part of a conspiracy. Ian is confined as a galley-slave, but the galley is wrecked, he is washed ashore and heads for Rome to find Barbara. But he is captured again and trained as a gladiator.
Poppaea is jealous of Barbara and decides to poison her. Ian is to be killed in the arena. The Doctor finds Nero’s architectural plans and figures out that it is 64 AD and Nero is planning to destroy the city. The time-travellers avoid death and leave in the TARDIS as Rome burns.
The story was played for dark humour, with Nero a pompous and foolish figure, like a Roman Benny Hill, and there are many near-meetings and popping in and out of doors as in a French farce or a Shakespearean comedy. The sets and costumes were impressive, if somewhat anachronistic, as in the fact that banqueters were shown sitting at table because the stage was too small to hold enough divans.