Olivia Finn is a memory expert at Charing Cross Hospital in London. One night, she receives an urgent call from the police at the Hotel Lutetia on Paris’s famous Left Bank. Olivia’s French...

What if your nightmares weren’t really nightmares at all? We spend an average of 33 years of our lives asleep. But what really happens, and what are we capable of, when we sleep? Anna Ogilvy was a...