The story is told by Mark Easterbrook, a writer who had taken up residence in the Chelsea district of London while working on his latest book on Mogul culture. He stopped into a coffee shop for a quick meal and witnessed an argument between two young women that ended with one pulling out a handful of hair from the other. The unfortunate woman's unusual name - Thomasina Tuckerton - stuck with Easterbrook. He was surprised when he saw it a week later, in the obituaries.
Easterbrook went on about his life, meeting with his friend, Ariadne Oliver, traveling to the country to visit his cousin, and going out with his long-time girlfriend Hermia Redcliffe. Meanwhile the police begin to investigate the murder of a priest who was killed on his way home from hearing a last confession. They found a list of names stuffed into the priest's shoe, including the name of the police inspector. The two threads of the story meet and continue to weave throughout London, out to the country, on to Birmingham and returning to London. On the way the path leads to witchcraft, deathrays, and murder for hire.
The mystery here appears to be more a how-it-was-done than a who- done-it although Christie has once again lead us down the garden path to a surprise finish.