The Doctor and Clara

In the TARDIS The Doctor offers Clara Oswald the choice where to go for their next destination. Clara insists that The Doctor takes her to meet Robin Hood, despite The Doctor's protestations as to his existence - claiming that Robin Hood is only a legend. To prove Clara wrong The Doctor sets course for Sherwood Forest, '1190ish' and soon the TARDIS lands in medieval England. While Clara changes her attire, The Doctor exits the time-machine just as an arrow hits the TARDIS. He is then introduced to a man who claims to be Robin Hood.

The Doctor is distrustful of Robin which results in Robin challenging The Doctor to a duel which The Doctor accepts. Watched by Clara the duel takes place on a narrow bridge over a river with The Doctor using a spoon instead of a sword. The result ends up with The Doctor pushing Robin into the river, only for The Doctor to be pushed into the water by Robin. Robin then takes The Doctor and Clara to his campsite to meet his band of Merry Men: Will Scarlett, Friar Tuck, Alan-a-Dale, Walter and Little John. The Doctor, however, is still convinced that Robin is a fake and deduces that maybe they could be inside a Miniscope (see "Carnival of Monsters"). Clara however, is enjoying her time with Robin and learns that he is still looking for his Maid Marian. The Doctor, even after taking various samples from the Merry Men to determine if they are human, is still convinced there is something wrong. He is also unhappy with the weather which is far too sunny for the time of year.

Meanwhile, in a nearby village, the Sheriff of Nottingham and his helmeted knights are taking away all the villager's valuables and also Master Quayle's maid. Quayle pleads with the Sheriff to take him instead and spare his maid but the Sheriff refuses killing Quayle as the knights taking the woman away screaming.

Robin Hood

Later, with Robin and his Merry Men, The Doctor and Clara attend an archery contest held by the Sheriff. Robin, disguised as Tom the Tinkerer, faces against the Sheriff in the final round to win the prize of a golden arrow. As legend states, Robin is able to beat the Sheriff by splitting his arrow with his own shot. The Doctor suddenly appears and challenges the result, and readily splits Robin's arrow with his own. The two begin to challenge the other with more arrows until The Doctor impatiently explodes the target using his sonic screwdriver. The Sheriff, intrigued by The Doctor's power, orders the competition to end and commands his knights to capture them. However the knights turn out to be disguised robots when Robin cuts off one of the knight's arms, revealing circuitry. With the true nature of the knights revealed all of the knight's helmets open, revealing their unemotional, robotic faces. The Sheriff, realising his game is up, orders The Doctor, Clara and Robin to be taken away and placed in the dungeon of Nottingham Castle.

In the dungeon the three of them are chained to a post. In trying to come up with an escape plan The Doctor and Robin bicker to a point where Clara's admonishments are seen to make her the leader by those watching, and she is taken to meet the Sheriff. Clara is able to manipulate the Sheriff into revealing his past and future plans - that he witnessed a spaceship crash and has been trying to repair it by collecting all the gold in the nearby land, so that he can use the spaceship to travel to London and take over the kingdom.

The Dual

Meanwhile, The Doctor and Robin manage to escape their confinement by uprooting the post they were chained to and, at a blacksmith's shop, break out of their chains. Then, still inside the castle they discover a spaceship originating from the 29th century that was set to reach 'the Promised Land' (as mentioned by the Half-Faced Man in "Deep Breath"). The Doctor realises that this spaceship must have fallen back through time before crashing on Earth. Disguising their spaceship as part of the castle, the robots took on the guise of knights. The Doctor realises the engines were damaged in the crash, and are leaking radiation into the atmosphere so causing the surrounding area to be more like the Sherwood Forest setting of the Robin Hood myth.

The Doctor also notes that the spaceship contains the myths and legends of Earth's history, including that of Robin Hood. The Doctor confronts Robin with this information showing him photos from books, stories and television shows that follow the adventures of Robin Hood. He now believes that Robin is a robot like the Knights. But then the Sheriff arrives with Clara and some Robots Knights. Robin escapes with Clara by jumping from an open window into the moat, leaving The Doctor to get knocked out and taken prisoner again.

Back at the campsite, and reunited with his Merry Men, Robin begins to doubt his own existence. Shaken by The Doctor's revelations about his future he commands Clara to tell him who The Doctor really is and what he knows about the legend of Robin Hood. Clara assures Robin that he can still be the hero, telling him of what she knows of him.

The Sheriff of Nottingham

Meanwhile, held captive in a gold refinery, The Doctor wakes up to discover that the robots are creating a 'gold matrix' to repair their spaceship's engines. However, The Doctor also realises that there is not enough gold in the area to fully complete the repairs and if the Sheriff should try to use the spaceship, it will destroy half the country.

With the assistance of the young woman, that was taken from the village, The Doctor manages to break free from his chains before leading the prisoners to revolt against the Robot Knights. When the last robot is defeated the Sheriff arrives and while attempting to persuade him to abandon his plan The Doctor tries to get the Sheriff to confess that Robin is also a robot. However, the Sheriff does not know what The Doctor is talking about. The Doctor realises, from the Sheriff's reactions, that his belief about Robin was wrong and that he is the real Robin Hood. At this point Clara, Robin and the Merry Men arrive to help. This prompts the Sheriff to challenge Robin to a duel during which Robin's arm is injured in the fight. Robin though is able to knock the Sheriff into a vat of molten gold, with the same 'surrendering' technique that The Doctor used against him in their earlier duel, so killing the Sheriff.

Realising that the spaceship, controlled by the few remaining robots, is about to take off, so destroying the castle, The Doctor and Clara help the surviving prisoners to escape to a safe distance. As they watch the spaceship take off The Doctor realises that in a few seconds it will explode due to the lack of gold but if they could shoot the golden arrow, from the archery contest, into the spaceship the gold content will give it the boost it needs to enable it to reach orbit and so detonate harmlessly. The Doctor, Clara, and Robin work together and the plan works: the spaceship reaches orbit and explodes killing the remaining Robot Knights aboard.

As The Doctor and Clara prepare to leave, The Doctor admits to Robin that he accepts his story is real, and confirms to him that he will be remembered as a legend rather than as a man. Robin takes a moment to accept this, and then reminds The Doctor, based on the stories that Clara told him, that he is a hero of similar background as well. When The Doctor continues to deny this, Robin Hood suggests that their role is not to be heroes themselves, but to inspire others to take on that role. The Doctor and Clara then depart, revealing that The Doctor has left Robin a gift - he has found Maid Marian and has brought her to be reunited with Robin. Maid Marian is revealed to be the woman who helped him lead the prisoners rebellion against the Robot Knights.