Felix is alone in his wine shop save for one customer, Thrasyllus, advisor of Tiberius. Felix appreciates his business, but fears the association with someone so heavily involved in Roman politics. A stranger, introducing himself as the Doctor, visits the wine shop, and he drinks wine with Felix.
Meanwhile, Tegan and Turlough, having got separated from the Doctor while he lectured them on Roman history, are lost. They make their way through the Roman streets, with Turlough trying in vain to keep Tegan from getting involved in the political conversations. He notices a carrying chair that they have seen several times, though Tegan pays it little notice.
The Doctor is intrigued by the mathematical calculations made by Thrasyllus, who, though drunk, explains to the Doctor what he sees in the stars' movements. Felix listens uneasily, worried that they might be caught, and even worries that the orphan boy begging outside might turn them in. He sends the boy out to find out what is happening in the forum. Thrasyllus brags that changes are coming, and that there will be a revolution with Tiberius in charge.
Turlough sees the carrying chair again, and before they can resist, Tegan and Turlough are captured by the bearers and taken to a man who introduces himself as Sextus Cornelius, a traveller. He recognises that they are travellers like him, and orders them to take him to the Doctor, of whom he has heard. Tegan is bound and placed in the carrying chair, while Sextus escorts Turlough down the street, keeping a firm grip on his shoulder. As the group makes their way toward the wine shop, a boy runs in front of them. It is the boy from Felix' shop, and he heads back to the shop to warn the Doctor that his friends have been captured.
Sextus' group arrives at the wine shop, and Sextus explains his plans to the Doctor. He has been trapped on Earth for forty years, and he taught Thrasyllus how to calculate navigation based on the stars. He planned to use this knowledge to get off Earth, but now he wants to change Earth's history, allowing it to advance faster. He needs the Doctor's help, and threatens to harm Tegan and Turlough if the Doctor won't help.
Sextus is unaware that the boy has sneaked back into the wine shop and brings two jugs of wine out to Sextus' guards. He then returns and throws another jug at Sextus. It hits him, but he quickly recovers and fights with Turlough. Sextus pulls out a weapon and shoots Thrasyllus, then the Doctor disables him. The boy tells Felix that he gave the guards wine mixed with olive oil, so they are no threat.
Thrasyllus realises that he was manipulated, and leaves the wine shop, promising that his time will come. Felix decides to take the orphan boy into his home. When a nova appears in the sky, Felix and the boy get ready for an influx of customers, and the Doctor leaves with his friends.
- Tiberius Claudius Nero is the stepson of Augustus.
- Tegan wanted to see the Colosseum.
- The Doctor tells Tegan and Turlough about Julius Caesar's assassination.
- Thrasyllus has visited Egypt and Babylon.
- Sextus Cornelius tries to use hypnosis on the Doctor but fails.
to be added