The journey starts the next day with the driver worried about the possibility of them getting stuck in the desert mud after their stop at Ar Rutba as there have been heavy rains in the area. Sure enough, the vehicle does become bogged down as it drives through the night and the men step out to assist in freeing it. As they work they realise that Smethurst is not assisting and when O'Rourke investigates he finds the Captain is dead in his seat. Loftus, a doctor in the RAF, suggests he may have hit his head on the roof the vehicle as it went over one of the heavy bumps on the ground and when he examines him declares that he cannot find an obvious wound. The only other possibility is that he was hit with something in the nature of a sandbag whilst the other passengers were asleep. As they discuss the reason why someone would do such a thing, Williamson remembers overhearing a conversation that Smethurst had with an unknown third party in Damascus where he said that he would keep quiet until they arrived in Baghdad but not a moment longer. Pyne joins in with his story of his own conversation with the dead man in the nightclub and Loftus also recalls Smethurst talking to Hensley about "a leakage" in his department. Recalling that Hensley said he always carried spare socks with him, Pyne suggests Loftus fetches these. Sure enough, one is found to contain wet sand. Pyne now knows the murderer.