Monday, 24 May, 11.32 a.m. Ted and Kat watch their cousin Salim get on board the London Eye. He turns and waves as the pod rises from the ground.

Monday, 24 May, 12.02 p.m. The pod lands and the doors open. People exit in all shapes and sizes – but where is Salim?

Ted and his older sister Kat become sleuthing partners since the police are having no luck. Despite their prickly relationship, they overcome their differences to follow a trail of clues across London in a desperate bid to find their cousin.

Ultimately, it comes down to Ted, whose brain runs on its own unique operating system, to find the key to the mystery.