The London Eye Mystery by Siobhan Dowd

The London Eye Mystery
322 pages; David Fickling
When Ted's cousin, Salim, disappears while riding the London Eye, it's up to Ted and his sister, Kat, to figure out what has happened. Ted comes up with many interesting theories because, as he states, his brain operates on a different system (he has been diagnosed as having a "syndrome"). Will one of these theories solve the mystery?