Kitty, Sam, Toby, Lizzie, Luke, Jemima, and Jessica take up Merlin's offer of places at his multiversal multiversity. All's well until Merlina, a scheming head of a neighbouring Research Centre, pays a visit and sets up an inter-multiversity contest, pitting the Terran Team, as Merlin calls them, against her own elite team. The young humans endure a series of life-threatening challenges: escaping ridiculously difficult situations, a frantic space race-and-rescue mission, and an Immersive Book Experience in which the two teams and their friends play the characters, with the loser losing everything. Will they win through and foil Merlina's plan to discredit Merlin?