Max Wheeler is worried about the audience at his radio shows — several of them have died recently. Meanwhile, the Doctor and Susan are in London, in 1963, but when they make a trip, they end up in the same area, only in 1955. They meet Max and his ex-wife Maxine.
Max explains his worries about his audience, and the Doctor makes the connection between these deaths and the TARDIS' inability to travel anywhere outside of London. After Max's producer, Jolyon dies, the Doctor deduces that the mysterious hum present in several BBC buildings is the cause.
Max tells his wartime story of the Shakers, aliens who were employed by the British military to kill any Germans that tried to occupy Britain. The Doctor realises that the Shakers are from another dimension, and they are using their different oscillations to kill humans.
The Doctor, with Susan, Max and Maxine's help, sets up a trap for the Shakers. They put on a radio show, with recorded laughter, which brings the Shakers out of hiding. Max uses his military experience to inform the Shakers that the war is over, but when they learn they were betrayed by the British government, they try to kill everyone. The Doctor is forced to kill them by altering the oscillation of the laugh track.
With the TARDIS now able to leave, the Doctor quotes the astronomical odds against the TARDIS landing back in Totter's Lane in 1963.
- Max thinks the Doctor might be a magician.
- Susan has been studying quantum theory, relativity and cricket.
- Maxine mentions influenza and TB as potential causes of death.
- The Paris Studio is located on Lower Regent Street.
- Max's radio show is called Anyway, As I Say.
- The Captain's Cabin is a pub.
- This story was reprinted in Short Trips: Re:Collections.