The Doctor

Alone, and on the trail of an alien artefact, The Doctor arrives in 1651 England. His tracking device leads him to a stagecoach belonging to the Fanshawes which is travelling through the woods. The stagecoach though has been stopped by a highwayman known as ‘The Knightmare’ who demands something specific of Mrs. Fanshawe. She seems to know what the rogue wants. However, at that moment The Doctor enters the carriage. Seemingly unaware that The Knightmare is in the middle of carrying out a highway robbery. He greets everyone in passing, saying he is tracking something.

The Doctor’s arrival annoys The Knightmare especially as The Doctor ignores the highwayman and is more interested in the tracker that leads him to a case on the back of the carriage, which the Knightmare attempts to stake a claim on. However, the carriage drives off before The Doctor can take the piece of luggage leaving The Doctor and the highwayman alone together by the roadside. With nothing else to do, The Knightmare unmasks, revealing himself to be Ashildr the Viking girl made immortal in the previous story (see "The Girl Who Died"), who can mimic a man's voice. The Doctor is surprised to see her, but is more surprised that she has forgotten her original identity due to the centuries that have passed. Ashildr now calls herself ‘Me’ as there is no-one who can remember her now.

Me takes The Doctor to her home, where he discovers that because of her 800 years of everlasting life she has lost many of her memories and has isolated herself in order to avoid the pain of losing loved ones. She now lives in a mansion thanks to hoarding treasure over the years. She vaguely informs The Doctor that she now has an accomplice, whose glowing yellow eyes watch The Doctor from the shadows. Me repeatedly asks The Doctor to take her away from this world and to take her with him to see the universe But The Doctor refuses despite her pleading.

Me

Me reveals that she dislikes keeping company with other humans, as they're lifespans are like smoke that can be blown away. However, The Doctor notes that she's tried to help humanity, even founding a leper colony. Me points out that when she helped cure a village of scarlet fever, she was drowned as a witch by the small-minded people, but was able to swim away. The Doctor sees that Me keeps several diaries, since her memory is still in its original human-limited form, thus keeping her from remembering everything that's happened. Flicking through one of her journals he finds some of Me's memories ripped out and pages stained by her tears. He also discovers that Me previously had three children, all of whom she lost to the Black Death. The pain of these events were recorded, so she didn't have to keep reliving them through the centuries. However, The Doctor deduces that the reason for the missing pages is because there were some things Me found too painful to remember.

Meanwhile Me talks to her accomplice, explaining that an alien like The Doctor would be useful in their plans. On returning to The Doctor she reluctantly agrees to let him help her steal the object they're both after from the Fanshawes. And so later, they break into the Fanshawe's estate, and find their prize: The Eye of Hades, a glowing purple jewel that The Doctor theorises is linked to ancient Greek mythology as a way of opening a portal to the afterlife or into space. On making their escape they accidentally awaken Mr. Fanshawe who starts a search for the intruders. Me is ready to kill, so as to escape, but The Doctor convinces her that they can escape up a chimney.

Lady Me

Escaping into the forest Me continues prodding The Doctor with questions. They are then surrounded by other highwaymen, lead by The Knightmare's rival - Sam Swift the Quick. Sam Swift, on recognising Me as The Knightmare thinks that The Doctor is her sidekick and father. This annoys The Doctor who taunts the thief for the redundant title. Me quickly disarms Sam Swift, sending him and his cronies fleeing in fear.

The next morning, The Doctor finds out that by day, Me is known as ‘Lady Me’ and lives as a wealthy woman with a servant. He then meets her ally Leandro, a lion-like alien stranded on Earth who was the artefact's original owner. Leandro wants to use The Eye of Hades to open a portal to leave Earth, but it requires the life energy of someone to work (in other words a death is needed). In return for Me tricking The Doctor into helping him, Leandro has agreed to let her come with him to travel the galaxy. They considered using Me's aged butler, but The Doctor opposes it.

Two pikemen then arrive to check on Lady Me as The Knightmare is reported to be in the area. They also reveal that Sam Swift has been captured and is about to be hung at Tyburn. Me, realising that luck is favouring her, informs the pikemen that The Doctor is The Knightmare's sidekick asking them to just imprison The Doctor due to his advanced age. She then sets off to use Sam Swift's death, instead of her butler, to activate the artefact. The Doctor tries passing himself off as an undercover officer from Scotland Yard, but realises this institution has not been founded yet. Seeing Me leave with Leandro in her carriage, The Doctor tells the pikemen guarding him that The Knightmare is escaping and that he wishes to go to the hanging. The guards inform him there's a twenty pound bounty on him, which is a treasure compared to their pay, so they'd rather not take him to be hanged. Realising that only money will tempt the pikemen to let him go The Doctor tells them where they can find Lady Me's treasure. This works and The Doctor pursues Me to the hanging.

Leandro Arrives

At the hangman's noose Sam Swift is making jokes to buy himself a few more minutes. The Doctor arrives assisting with Sam Swift's delay even using his psychic paper to fake a pardon for him from Oliver Cromwell. However, Me manages to overrule the comedy and so the hanging begins. In a last desperate attempt Sam Swift asks for a kiss as his last request. Me complies but uses this as an opportunity to attach The Eye of Hades to Sam Swift's chest so killing him. A portal opens and Leandro reveals himself, breathing fire in triumph, revealing that he is an advanced scout for his people and his actual intent is to assist his people in invading Earth.

Spaceships begin firing at the crowd gathered to watch the hanging. Me, rediscovering her conscience and humanity, after seeing the crowds being slaughtered, and uses the second Mire medical chip, given to her by The Doctor, to save Sam Swift's life. The excess of life energy causes The Eye of Hades to backfire and the portal closes. Leandro is vaporized by his fellow warriors for his failure.

Later, in a tavern, Me wonders if Sam Swift is now immortal like her. The Doctor explains that Sam Swift may or may not have been rendered immortal by the chip as its power could have been drained when closing the portal. However, just in case Sam Swift is immortal, he asks Me keep an eye on him. It's at that moment that Me realises why The Doctor won't take her with him; it's because her view point is too much like his own, and he needs someone who sees things differently. The Doctor mentions having travelled with another immortal named Captain Jack Harkness, and that she may be running into him in the future. Me then says she'll take the role most of the others that have met The Doctor have, protecting the world from his good intentions.

Back in the TARDIS, The Doctor is playing his electric guitar deep in thought. Clara Oswald arrives and The Doctor accepts her hug. Clara explains that The Doctor's idea of taking one of her pupils to meet Winston Churchill has paid off. The Doctor looks at the selfie Clara has on her phone, taking note that Me is the background, looking straight into the camera. The Doctor though pretends that nothing is wrong.