The Doctor (Jodie Whittaker), Graham (Bradley Walsh), Ryan (Tosin Cole), and Yasmin (Mandip Gill), are taken by transport cube to Tranquillity Spa for a vacation. They are welcomed by Hyph3n (Amy Booth Steel). Ryan obtains a snack from a vending machine and is infected by a Hopper virus. The Doctor is able to extract the virus, and in Recovery he meets an attractive fellow guest named Bella (Gia Ré). But there is a breach and guests are asked to assemble for a muster drill. The Doctor asks Hyph3n to allow her access to the Linen Cupboard, which is actually a security room with an armoury, where they meet Kane (Laura Fraser). The Doctor wonders why there is an ionic membrane to protect a holiday spa. But the creatures who broke in begin to kill the guests and the Hopper Virus infects the spa’s systems, disabling the transporter and security cameras.
The survivors, the mechanic Nevi (James Buckley), his son Sylas (Lewin Lloyd), and an old woman named Vilma (Julia Foster) meet in the Linen Cupboard. But Vilma’s partner Benni (Col Farrell) is missing. The Doctor builds a new ionic membrane to banish the creatures, who are the local Dregs. The spa is really a fakation, which is a fabricated environment designed to look like a vacation. Benni is recorded outside the spa, so they go out to rescue him. They see that the planetscape is desolate and uninhabited. It is called Orphan 55. Their vehicle is caught in a Dreg trap and is surrounded by Dregs. Benni is their hostage. They all run for a service tunnel, but Hyph3n is killed by Dregs and Benni is shot by Kane.
In the tunnel, Bella reveals that she is Kane’s neglected daughter. Bella escapes with Ryan in the transporter and the others try to use the stairs, which are swarmed by Dregs. The Doctor, Yaz, and Graham find a rusted sign in Russian and learn that Orphan 55 is actually Earth after climate change and nuclear war, and the Dregs are mutated humans. Vilma sacrifices herself to help the others escape, and Kane stays behind to do the same. Bella tries to destroy the spa in anger at her mother. Surrounded by Dregs, they fix the transporter and escape, leaving Bella and Kane behind to fight the Dregs. In the TARDIS, the humans despair over Earth’s future and the Doctor doesn’t have much hope to give them.
The episode was written by Ed Hime and directed by Lee Haven Jones. It was filmed in Tenerife near the dormant volcano Teide. Much of the dialogue was dubbed in during post-production. The plot is quite similar to that of Midnight (2008) with David Tennant. It was not well received by critics, criticized for pacing, silly costumes, too many characters, with a timely message “banged home with a sledgehammer”. The original idea was quite different from how it came out. It actually had the lowest IMDB viewer rating of any Doctor Who episode since 1963. Despite a nice comic turn by Tosin Cole, the Dregs being somewhat cool, and the serious message, it doesn’t have a lot to recommend it.