The incident of the book in the nighttime

Gemma Doyle and her friends have packed their bags and headed to London for her sister Pippa's wedding. Waiting for her in the hotel lobby is none other than Gemma's ex-husband, Paul Erikson. Paul has a rare book he wants her to see -- calling it "the real deal" -- so Gemma agrees to meet him at their old shop, Trafalgar Fine Books, the following day. But when Gemma arrives, accompanied by Grant, a rare book dealer, they find Paul dead in his office. Paul had been down on his luck, but Gemma never expected this. Had he borrowed money from people he shouldn't have? And where is the valuable book he was so anxious for Gemma to see? It's nowhere to be found in the shop. Because of their previous relationship, Gemma feels she owes something to Paul and vows to find his killer. As Gemma and her best friend Jayne Wilson follow Paul's trail of friends, enemies, clients, and ex-lovers through London to Yorkshire, she realizes the puzzle of Paul's last days is more twisted than she originally thought. This mystery is anything but elementary, and Gemma and Jayne have to use all their wit to get to the bottom of it before their time in London -- or in life is over.