Father Brown investigates when rivalries escalate to murderous heights at the Kembleston Olimpicks.Mrs Devine is shocked when her son Eddie returns to Kembleford. She is determined to keep her new relationship with Chief Inspector Sullivan a secret from everyone, although Father Brown and Brenda know exactly what's going on!Soon the competitive nature of the games starts to show, with disgruntled gardener Patty Frewin blaming Dr Geoffrey Fleming for her withdrawal from the competition, while Shirley Fraser is also unusually edgy around the doctor. Elsewhere, Geoffrey disqualifies his own brother Brian, much to the delight of Hambleston captain, William Redshaw. When Hambleston competitor Ursula Fanshaw is poisoned during the spinach eating contest, it soon transpires that Geoffrey was the intended target. Can Father Brown identify the killer before they strike again?