Detective Brunel (Lino Ventura) investigates a mysterious series of disasters. The events begin happening shortly after writer John Morlar (Richard Burton) is hit over the head by an unknown intruder and rendered comatose. Slowly, Brunel begins to connect the strange things that are happening with the deranged dreams of the comatose Morlar. He gets the final clue from Morlar's psychiatrist, Dr. Zonfield (Lee Remick), who holds the key to Morlar's past. Once it is discovered that Morlar has the ability to think horrible thoughts and make them come true, Brunel and Zonfield must hurry to a London cathedral, where the Queen is scheduled to make an appearance — but Morlar is thinking about the cathedral, and it is crumbling fast.