The basic story: The police, with the assistance of a famous private detective working for an anonymous employer, are investigating the death of Harlan Thrombey, a famous mystery writer. Harlan's death appears to be a clear case of suicide. After his birthday party, he played a game of Go with his caretaker, Marta Cabrera, and then, after she left, laid down and slit his own throat.
However, something doesn't quite add up. Why was a famous detective like Benoit Blanc hired to look into Harlan's death? On the day of his birthday, Harlan cut his financial ties to several members of his family. If he was actually murdered, there are quite a few potential suspects. And Marta, who can't lie without needing to throw up, knows more about what happened that night than she's saying.
