Christmas is approaching. Aerin, Sherlock, and Arsène find themselves in London. And while Sherlock is in a bad mood, a sudden mystery sweeps the three friends into a terrifying adventure. The director of the British Museum has been murdered under very enigmatic circumstances, and the newspapers speak of a dark curse that has its roots in ancient Egypt. Aerin, Sherlock, and Lupin immediately begin their investigation, unraveling the threads of a very strange case whose solution will be unexpected and unpredictable.