Corakinus finds a way to retake his throne and strikes at the teenagers who defeated him by killing their loved ones. To stop Corakinus and the Shadow Kin, Charlie and April must make the ultimate sacrifice.

After locking the students in detention, Quill goes on a quest to remove the Arn from her head... or die trying.

The students are trapped beyond time and space when an asteroid hosting an alien consciousness crashes into their detention room. They will each have to confess their deepest truths if they have any chance to escape... or live.

While April and Ram travel to the Underneath to fight Corakinus, Dorothea forces Charlie to choose: sacrificing his people's souls to stop the petals, or watch Matteusz die.

April tries to deal with Corakinus' influence as he tries to restore his missing heart. Meanwhile, her father Huw pays a visit, and carnivorous flower petals start covering London.

When London is infiltrated by a powerful alien, an unexpected visitor comes to Tanya's window. The team must battle this strange new threat to stop Tanya from being lost forever.

While Ram struggles to cope with his girlfriend's death and the other events at the Prom, he isolates himself from the others. Then he sees a skinned carcass and the others soon have a similar encounter. With the school facing a new menace coming through the rift, the gang must unite to fight it.

Four students at Coal Hill Academy are swept up into an alien invasion when the Shadow Kin come through a rift in space-time looking for the Cabinet of Souls.