I read this after having watched most of the TV show – and I amused myself by working out which characters had been used for that, and which hadn't. The book gives an explanation for the phenomena, refreshingly, no terrorists or criminals are involved – no evil Arabs or crazy women. This book is both science-fictional and philosophical – a tad depressing, and a bit sweary, but overall, a very good read. The characterisation is very good, everyone is well-rounded and no one is a cliched ‘type’.