Arriving For School

Clara Oswald is struggling to maintain two separate lives: one as The Doctor's travelling companion and the other as a school teacher at Coal Hill School where she is having a relationship with fellow teacher Danny Pink. Danny though starts to become suspicious when, after an adventure on a desert planet, Danny notices she’s developed a tan since he last saw her and while an encounter with fish people leaves seaweed in her hair during a date.

However, while preparing for their next outing The Doctor informs Clara that she cannot join him as he is going 'deep undercover'. The next morning Clara is in for a shock when, in the school staffroom, the head teacher presents a temporary caretaker: The Doctor, under the alias John Smith...

Clara eventually learns of The Doctor's actual purpose at the school and the presence of a murderous robot called the Skovox Blitzer that is located nearby which has enough firepower to destroy the planet. Clara tells The Doctor to leave it alone, but The Doctor explains that if he does not act, someone will discover and attack it and so prompting it to begin destroying Earth. He intends to draw it to the school at night when it is empty and use a time vortex to displace it a billion years into the future where it can not harm anyone.

Let me Introduce the New Caretaker

Being the school's caretaker enables The Doctor freedom to plant devices around the school that will generate the time displacement vortex. He also demonstrates to Clara an invisibility watch, which he will use to avoid detection by the Skovox Blitzer. But one of Clara and Danny's students, Courtney Woods, becomes suspicious of The Doctor when she sees the TARDIS hidden inside his cupboard.

While working at the school it is not long before The Doctor gets to meet Danny and on learning he is a former soldier The Doctor shows disdain and they have a conflict over what Danny teaches. Danny claims to have been a soldier who now teaches maths, while The Doctor instead thinks he teaches PE, as this would make more sense due to him being a soldier. But The Doctor doesn’t realise Danny is Clara’s boyfriend, instead thinks that this is another school teacher called Adrian, who resembles his previous incarnation, the Eleventh Doctor. Because of this The Doctor states that he approves of Clara's relationship with Adrian.

Clara Confused

Working late, Danny however, discovers some of The Doctor's devices and inadvertently changes the settings of the devices. Unaware of this The Doctor lures the Skovox Blitzer to the school in the evening when it is deserted but due to Danny's interference the Skovox Blitzer is only displaced 72 hours forward in time.

After witnessing the chaos, Danny realises Clara’s has lied to him and is shocked to learn of Clara's double life, assuming that she is an alien and The Doctor is her father. Clara has no choice but to tell him the truth: that even though she is human, The Doctor is the alien and that they travel through time and space together in the TARDIS. To prove this The Doctor shows Danny the inside of the TARDIS. Danny though asks Clara why she travels with him, which she attributes mostly to the wonders that she experiences. Danny struggles to accept this and he wonders whether Clara loves The Doctor romantically, which she denies.

The following day, and to convince Danny that what she has said is the truth, Clara allows Danny to observe her interactions with The Doctor, with him wearing The Doctor's invisibility watch. However, while building a device to fight the Skovox Blitzer, The Doctor sees through this and when Danny makes himself visible an argument arises between them out of mutual disdain of each other before Clara blurts out that she loves Danny.

The Doctor on a Mission

Later that day, during a parents' evening at the school, the Skovox Blitzer re-materializes earlier than The Doctor estimated. On discovering this and with Clara acting as a decoy, using The Doctor's sonic screwdriver to attract the Skovox Blitzer, the creature is lured into The Caretaker's cupboard where The Doctor is waiting with the device he built. It is a communication device that makes the Skovox Blitzer think The Doctor is its superior. Unfortunately when The Doctor instructs the creature to deactivate he accidentally triggers its self-destruct protocol. To prevent catastrophe The Doctor has to deduce an authorisation code that will stop the self-destruct count down. He tells Clara to distract it while he hurriedly tries to prepare the code, but she is unsure what to do. Just then, Danny arrives, despite being told to stay away, and is able to distract the Skovox Blitzer long enough for The Doctor to give the final code, deactivating the Skovox Blitzer for good.

Soon after The Doctor takes the Skovox Blitzer into space and ejects it from the TARDIS, taking Courtney on her first trip. Unfortunately, she is unable to cope with the immensity of the universe and finds herself feeling rather ill.

Back on Earth, during a heart-to-heart, Danny tells Clara that The Doctor reminds him of previous commanders he has known, who push their soldiers to get them to do more than they realised they were capable of. Even though he is impressed that The Doctor can push her to act without fear he is worried that The Doctor might push her too far. He therefore insists that Clara must promise to let him know if The Doctor pushes her too far so that he can help her.

Meanwhile, a police officer who was vaporised by the Skovox Blitzer, while investigating a mysterious noise coming from a rundown building a few days ago, awakens in a long white office corridor with many doors. An interviewer, behind a desk, informs the police officer of his death and their whereabouts. As the mysterious Missy appears further down the corridor the interviewer tells CSO Matthew that the place has many names, including the 'Promised Land', but he prefers to call it 'The Nethersphere'.