The TARDIS lands during the French Revolution, where Ian, Barbara, and Susan become caught up in the politics of the day. When they are arrested and set to be executed, the Doctor must take on the disguise of a public official to try and save their lives.

Susan, Ian and Barbara are sentenced to be guillotined but an encounter with a dying English prisoner may offer Ian a chance of survival.

Susan and Barbara are rescued by Jules and Jean, two members of the escape chain, while the Doctor gains access to the prison by posing as a revolution official.

The Doctor is forced into a meeting with Robespierre while Barbara's attempts to find a physician for Susan result in them being betrayed.

Ian finds himself held prisoner by the treacherous Leon while the Doctor attempts to engineer Susan and Barbara's escape.

Ian finally delivers his message to James Stirling but in order to secure Susan's release he and Barbara are forced into a dangerous spying mission.

Ian and Delos are forced to fight each other for their freedom while the Doctor has to perform for Nero's court.

Ian and Delos manage to escape from Sevcheria and Tavius agrees to help Barbara rejoin them.The Doctor's attempts to avoid being thrown to the lions inadvertently result in Nero deciding to burn down Rome.

The Doctor, Vicki, and Steven Taylor, go to 1066 England, but something doesn't seem right including modern inventions like a Gramaphone and electricity. Could there be another Time Lord?

The Doctor is being held prisoner by the Monk and Steven and Vicki's search for him brings them to the Saxon village.But a greater danger threatens when a Viking raiding party arrives.

The Doctor manages to escape from his cell and get the upper hand on the Monk but his plans are derailed when Sven and Ulf arrive at the monastery.

The Doctor finally discovers what the Monk is up to and must move fast to prevent his opponent from altering the course of history.

The Doctor, Steven and Sara escape Mira in a Dalek pursuit ship but when they find the ship is returning to Kembel, they are forced to come up with a new plan to avoid the Daleks.

The Daleks realise the Doctor has given them a fake Taranium Core while, on the planet Tigus, the Doctor encounters the Meddling Monk.

The Doctor, Steven and Sara travel to Ancient Egypt, pursued by both the Daleks and the Meddling Monk.

Steven, Sara and the Monk are captured by the Daleks in order to force the Doctor to hand over the Taranium Core.

The Doctor, Steven and Sara reach Kembel where they find the Daleks have betrayed their allies and imprisoned them.

With the Daleks poised to invade the solar system, the Doctor decides his only option is to activate the Time Destructor prematurely, threatening the entire planet.