Aliens in the Blood

Following on from the conclusion of the first series of Class, Charlie knows he has made a mistake. With his boyfriend, Mattuesz in pursuit, Charlie runs off, leaving the relative comfort of his life behind he heads out into the unknown. One night, he decides to call the Doctor and confess to what he has done using the Cabinet of Souls as a weapon. Using a distress beacon that the Doctor gave him, he calls his former saviour. Only it is the wrong Doctor, who turns up. A previous incarnation of the Doctor, who doesn't know who Charlie is. Has never heard of the Shadow Kin. And then humans start to turn into aliens...