It has been continuously raining for four days in Peckham, and the Trotters have not been able to sell any of their sun hats.
At The Nag's Head, Del Boy meets his friend Alex, an out-of-work travel agent.
When they get to Benidorm, Del and Rodney manage to pick up a couple of girls, but when they go back to their hotel room, they find Grandad asleep with his false teeth by his bedside.
A few days later, on the beach, Rodney and Del discuss how Grandad has been acting nervous and emotionally distant since they arrived.
At the police station, Grandad tells his grandsons a long and confusing story about a possible reason for his arrest: in 1936, when his family was poor, Grandad and his friend Nobby Clarke hitchhiked all the way to Southampton, got a boat to Tangier, and, after a failed attempt to join the French Foreign Legion, became gun-runners during the Spanish Civil War.