Katarina is wandering in the Underworld, barely remembering who she is. An old woman talks with her, helping her to remember who she is. Katarina is humble, accepting that she is not worthy of the Elysian Fields, but the woman thinks she is, and arranges for the Doctor to help Katarina. Katarina is shocked, realising who the woman is.
The Doctor appears and realises where he is. Katarina explains that she needs a coin for Charon so that he will ferry her across the river to the Plain of Judgement. The Doctor has no money, and his pleas to Charon fail. The Doctor, finally, offers his signet ring as a fare. Charon agrees, but only one may cross. However, he refuses to carry Katarina, as she is unclean.
The Doctor once again appeals to Charon, gripping his arms. Charon turns away, but realises that the Doctor has taken his gold. The Doctor scatters the coins, and when Charon scurries to pick them up, the Doctor and Katarina escape in Charon's boat.
After some difficulties, they reach the opposite shore, where Cerberus awaits. Whenever they try to pass, the three-headed dog awakes and bars their passage. The Doctor fashions a dog-whistle and contrives a device allowing the whistle to sound continuously. While the music keeps the dog occupied, he and Katarina make their way past it.
Further down the path is the dividing road, where the Judges of the Dead await. They weigh Katarina's deeds in life with pebbles on a scale. Finally their judgement is revealed — she is neither good nor evil and will spend eternity wandering the fields with the others who have sinned. The Doctor refuses to accept this decision. He goes to the highest authority — Hades.
Hades angrily refuses to overthrow his judges' decision. He orders them to bow before him, but the Doctor refuses. Katarina expects to feel Hades' wrath, but his wife Persephone approaches. She was the old woman that brought the Doctor to the Underworld to help Katarina. She pleads Katarina's case and convinces Hades that Katarina was misjudged.
Hades relents, and Katarina is allowed to enter the Elysian Fields. She bids a final farewell to the Doctor, and he disappears.
- The stories in Short Trips: The Muses are inspired by the Muses of Greek mythology. This story is based on Calliope, the Muse of Epic Poetry and Rhetoric.
- This short story tells what happened to Katarina after she met her death in TV: "The Traitors". It is one of the few licenced Doctor Who stories to deal with the concept of an afterlife. Even more rarely, it depicts an explicitly classical fantastical afterlife, and no attempt a scientific or pseudoscientific explanation is given.