Clara Lost In Space

This story starts with Clara floating in space desperately calling the TARDIS to be rescued. However, The Doctor is busy trying to resolve a conflict and is having trouble locking on to her location. Clara then realises that something is in her spacesuit; The Doctor suggests it is a brain-eating parasite called a Love Sprite. Within moments of it getting too close to Clara's head The Doctor materialises the TARDIS around her. As Clara re-adjusts to no longer being weightless The Doctor takes off her helmet and kills the creature.

The Doctor decides to land the TARDIS to check on any damage. However, the moment they land they are surrounded by Vikings. The Doctor tries to frighten them by brandishing his sonic sunglasses but an unimpressed Viking simply takes the glasses and snaps them in two. Seeing that he should have had a backup plan The Doctor realises that he and Clara have no choice but to be taken prisoner by the Vikings.

The Doctor and Clara are enchained and escorted by the Vikings to their village. On entering the village the leader gifts a girl named Ashildr with the right half of The Doctor's sonic sunglasses which she seems to think is a weird kind of eye patch. Clara wonders if The Doctor has a plan, which he does. Freeing himself The Doctor loudly declares that he is cross with the Vikings, tossing his yo-yo upwards. ‘Surely, you would recognize the sign of Odin’. The Vikings though dismiss him as an impostor, to which The Doctor begins protesting until the image of a man who looks like Odin appears in the sky. Realising that he has been outdone The Doctor gives up the ruse.

Capture by the Vikings

Odin commends the Viking warriors' bravery and invites them to Valhalla. A squad of armoured suits then arrive and begin scanning the townsfolk, rounding up the most fit warriors. They then use weapons that appear to disintegrate the Viking warriors. The Doctor deduces they are using advanced imaging to target the Viking warriors and are teleporting them away. Clara tries getting Ashildr to use part of The Doctor’s sonic sunglasses to open her cuffs, but this alerts the sentries and the two women are struck by the weapons after the sonic technology was scanned. The armoured suits then disappear, leaving The Doctor alone with the non-warriors of the village.

Clara, Ashildr, and the other Vikings find themselves aboard a spaceship. Clara notices that her cuffs are off and that the Viking warriors are impatient to meet Odin. One tries opening a door in front of them, only to be zapped into dust. Clara and Ashildr manage to open the door, barely escaping the next zap that reduces the other Viking to dust as well. On exploring the corridor they come face-to-face with Odin, who is actually the leader of the Mire, a species that prides itself on its merciless reputation and who are killing the male Vikings so they can be drained for their adrenaline and testosterone. Clara attempts to negotiate peace but Ashildr, now knowing her people have been tricked and so enraged by what she has seen, declares war for her people. Odin though welcomes it, stating that he will launch an attack in 24 hours and returns Clara and Ashildr back to the village - much to the relief of The Doctor.

Ashildr

Clara quickly brings The Doctor up-to-date explaining Ashildr's blunder. The Doctor, on reading his 2000 Year Diary, discovers that the Mire are a deadly warrior race, like the Sontarans, but they typically leave others alone if they get what they want. The Doctor therefore tries to encourage the remaining villagers to abandon the village until the Mire have left. They refuse, due to their pride, as they are willing to make a stand despite their lack of battle skills. The Doctor therefore has no option but to teach them basic combat. But he soon realises that they are far too weak and incompetent to stand up to the Mire. The Doctor tries to devise another plan. He discovers that Ashildr is a storyteller who uses homemade articulated puppets. Able to understand ‘Baby’, he translates for the blacksmith's baby, who is crying about the ‘fire in the water’. The Doctor realises that this refers to the electric eels that the fishermen have caught, and this becomes the basis of his plan to save the villagers. The Doctor, on this stroke of genius, rounds everyone up and begins setting up a nasty surprise for Odin and the Mire.

The next day Odin and the Mire arrive and are lured into a barn where they find the villagers having a party. Confused by this the Mire hesitate to attack. On The Doctor's cue, a bucket of eels is startled; their electric charge is channelled into an anvil in the barn, creating a magnetic field that lifts the Mire soldiers' helmets off. The Doctor quickly modifies one of the helmets and gives it to Ashildr to wear. Mental images from her stories are then relayed through the helmets to the other Mire, and the invaders see a dragon attacking them. The Mire flee, leaving Odin behind. Ending the ruse, The Doctor reveals that the dragon was just one of Ashildr's puppets augmented by her imagination and that Clara has recorded the Mire's terrified rout on her phone.

The Doctor then threatens to upload this recording, showing Odin’s embarrassment, to the Galactic Hub (and thus ruin the Mire's reputation) if they don't leave the planet peacefully. As Odin fears the loss of his reputation, more than an actual loss in combat, he agrees and the Mire spaceship departs.

Odin

The Doctor and Clara then discover that Ashildr was killed in the battle - the strain of using the Mire’s helmet causing heart failure. The Doctor is upset and is brooding about the loss. Clara tries to console him but to no avail. The Doctor on seeing his reflection realises why he chose his face and remembers back to when he first saw it, wondering once more ‘who frowned me this face?’ It is at that moment that his memory comes back to him; Previous companion Donna Noble had encouraged him to always try to at least save someone even in a fixed point, and he saved Lobus Caecilius' family from Pompeii's destruction. He tells Clara that he chose this face to remember to always save someone. Despite knowing that he is breaking the ‘rules’ again to save Ashildr. He takes a chip from the Mire’s helmet and rushes over to Ashildr's corpse. He places it on her head and activates it, bringing her back to life – announcing that the chip is a medical kit for the Mire soldiers. He then gives her father a second chip telling him it is for whoever she wants.

With the villagers celebrating The Doctor confides to Clara that what he has done may be worse than death as the implanted chip will never stop working. That it will keep repairing Ashildr so preventing her from dying - effectively making Ashildr immortal. The Doctor also explains that immortality is not simply the inability of a person to die, but the agony of watching everyone they care about die. Therefore the second chip is for Ashildr to give away when she finds someone she cannot stand to live without and so prevent her from being alone for eternity.

On returning to the TARDIS, The Doctor is left wondering if he did the right thing. Clara though assures him everything will be fine, because what he did was born of good intentions.

Ashildr is then seen in a montage of time passing her by, but with age never affecting her. As she watches the world age around her, her expression changes from elation and wonder, to sorrow and misery, and finally hostility.