Under the unforgiving sun of the Syrian Desert, the eccentric English archaeologist Lord Greville Boynton and his son Leonard are seeking the final resting place of the head of John the Baptist. On the verge of this incredible discovery they are joined by Lord Boynton's second wife, the dominating, fabulously wealthy American Lady Boynton, shadowed as ever by their adopted American children - devastatingly handsome Raymond, put-upon Carol, and their troubled younger sister Jinny. Holidaying in Syria, the world famous detective Hercule Poirot is irresistibly drawn to the excavation, but this is soon over-shadowed when Lady Boynton is found murdered under the roasting sun and her financial empire is completely wiped out... Commissioned to find her killer by his old friend Colonel Carbury, Poirot soon realises there is no shortage of candidates. Besides her much maligned family, the dig has attracted an unusual group of travellers which includes the witty psychiatrist Dr Gerard, the laconic Jefferson Cope, the beautiful and resourceful Dr Sarah King, and the unconventional travel writer Dame Celia Westholme. As Poirot's little grey cells begin to sing and make sense of the case, the mystery suddenly deepens when Jinny and Sister Agnieszka, a Polish nun on pilgrimage, are attacked in the night and the Boynton family Nanny suffers a crushing breakdown. Each of the suspects has a motive for killing the despised Lady Boynton, but only the little Belgian detective knows which of them arranged her Appointment with Death...