Synopsis of Gambit
Sally Blount’s father, Matthew Blount, has been arrested for the murder of Paul Jerin, a chess master. Blount had arranged for Jerin to play twelve simultaneous games of blindfold chess at his club. Well into the contest, Jerin complains of physical discomfort and cannot continue. Shortly thereafter, Jerin dies of what tests show to be arsenic poisoning.
During the contest, Jerin had been sitting by himself in a small library off the chess club’s main game room. He had nothing to eat or drink except a pot of hot chocolate, brought to him by Blount. After Jerin fell ill, he was diagnosed by a doctor who was playing in the contest; the doctor called for an ambulance but Jerin died at a hospital.
Not only had Blount brought the hot chocolate to Jerin, he had washed out the pot and the cup after Jerin complained that he didn’t feel well. Blount is charged with murder.
The only people to enter the library where Jerin sat, other than Blount, were four messengers, who relayed the moves between the main game room and the library. The messengers apparently had no good opportunity to put arsenic in Jerin’s chocolate.
Dan Kalmus is Blount’s corporate lawyer, and represents Blount after he has been jailed without bail. Blount’s daughter Sally is convinced, however, that Kalmus is in love with Blount’s wife Anna, and that he won’t be inclined to give Blount his best legal efforts. Furthermore, Kalmus’ specialty is business law, not criminal law, and he might not have the needed background.
But Sally is certain that her father is innocent, so she hires a reluctant Wolfe to investigate on her father’s behalf.
Synopsis from https://en.wikipedia.org/wiki/Gambit_(novel)