The Doctor (Peter Capaldi) and Clara (Jenna Coleman) land in Sherwood Forest in 1190, where they run into Robin Hood (Tom Riley). He challenges the Doctor to a duel, and the Doctor knocks him in the river. Clara believes Robin Hood is looking for Maid Marian, but the Doctor does not believe he’s real. The Doctor interrupts the archery contest with the Sheriff of Nottingham (Ben Miller) by using his sonic screwdriver to explode the target. The Sheriff orders his robot knights to capture the Doctor. He allows them to capture him, Clara, and Robin to find out what’s going on.

The Sheriff intends to use a crashed spaceship, which looks like a castle tower, to take over the world. They need gold to repair the engine and have scoured the countryside for this. The Doctor thinks the engines will explode and destroy half of England. At first, he thinks the robots created Robin but eventually comes to believe he’s real. Clara and Robin escape, but the Doctor is recaptured. He leads a revolt which destroys most of the robots. Robin defeats the Sheriff with a trick the Doctor taught him.

The spaceship takes off but still lacks the power to escape Earth’s gravity. The Doctor decides to fire the golden arrow into the ship, adding a bit more gold so it may reach orbit before it explodes. The Doctor, Clara, and Robin have to work together to do this. Robin says he began his career the same way the Doctor did and does much the same work. Both deny they are heroes, and their job is to inspire others. The Doctor and Clara leave, and Robin stays with Maid Marian.

Skeptical about the legend, the Doctor thinks at first that they are in a miniscope, like the Third Doctor in Carnival of Monsters. One of the images of Robin Hood that the Doctor shows is that of Patrick Troughton, the Second Doctor, from the 1953 Robin Hood TV series. A beheading scene was cut out because ISIS had been beheading journalists. The Doctor recalls duelling with Richard the Lionheart, Cyrano de Bergerac, and Errol Flynn. The episode was called witty, entertaining, and silly. Writer Mark Gatiss called it frivolous, which I think is about right.