The Doctor has been working as a lecturer at a university when he befriends a kitchen staff worker named Bill and accepts to be her tutor. As time goes along, the mystery is placed as The Doctor is guarding something in a vault with the help of his assistant, Nardole, underneath the university. Meanwhile a friend of Bill finds a mysterious puddle that can mimic human life and apparently has an interest in Bill. Asking The Doctor for help, she is caught in the time traveler life of the Time Lord in an adventure all around the universe.
