The episode begins with a conflicted Clara, struggling to find the balance between her life with the Doctor and her life on Earth. Immidiately after it throws to Clara and Danny Pink upon arrival at Caol Hill school. A meeting of the teachers ensues and the Doctor is introduced by the head master as John Smith, the new caretaker. As expected Clara makes a fuss of him being there and in a rather lacking disguise. This episode revolves immensely around Clara and Danny's relationship as we finally see Danny meet the Doctor.
The enemy of this episode is the Skovox Blitzer, an alien artificial intelligence that is preprogrammed for destruction.
The Doctor reveals to Clara that the Skovox Blitzer is hidden nearby (An abandoned warehouse) and has enough fire power to destroy the planet.
'Skovox Blitzer, one of the deadliest killing machines ever created. Probably homed in here because of artron emissions, you've had enough of them in this area over the years; it has enough explosives in its arsenal to take out the whole planet.' - The Doctor
He explains that he is creating a plan to displace it in time, a billion years in the future where nothing can be harmed. Soon after a police officer spots to kids from Coal Hill and tells them to get back to school or he will take their names. Upon their leaving the police officer heads into the warehouse to investigate a noise he suspected to be more students. However the noise turned out to be the Skovox Blitzer and he was subsequently killed.
While laying out the chronodine generators, the Doctor encounters Danny, discovering that he was once a soldier. Soon afterwards, the Doctor assumes that Clara has an interest in another teacher: Adrian, whom he approves of. Without specifying Adrian, the Doctor states that he approves of Clara's relationship.
While he was working late, Danny comes across some of the Doctor's devices, unknowingly changing the settings in his investigations. The Doctor then lures the Skovox Blitzer to the school; due to the changing of the settings, the Doctor is only able to displace the creature a mere 74 hours in the future. Scolding Danny for meddling with his plan, the Doctor is shocked to learn that Clara is in love with Danny. Danny is also shocked to learn of Clara's double life, assuming that Clara is an alien and the Doctor is her father; maybe a throw back to the first Doctor and his niece.
Explaining the truth to him, Danny observes Clara's interactions with the Doctor. While doing so, an argument brews between the Doctor and Danny, due to a display of dislike for each other; the Doctor dislikes soldiers, and Danny dislikes officers assuming that a Time Lord is a senior officer class.
'Humans, I never learn' - The Doctor
Later that evening, the Skovox re-appears far too early. With Clara's assistance, the Doctor is able to almost assume control of the Skovox; with Danny's last minute intervention, they are able to order the Skovox to stand down by using a voice manipulation device to speak the Skovox's language. The Doctor later sends the Skovox into space, away from all lifeforms with a young student in tow; Courtney Woods.
Afterwards, Danny explains to Clara that he is impressed that the Doctor can push her to act without fear, though he tells her to let him know if he pushes her too far, so that he can help her.
In the final scene, the police officer awakens in the Promised Land, speaking to a previously unseen interviewer, who explains that Missy is busy.