Among the 'little ships' setting off for Dunkirk are three very different vessels. There is a London fireboat manned by Olly Mears and his crew, a pleasure steamer from Devon commanded by Able-Seaman Robby Endacott, and a small motor yacht owned by Hubert Stainbank and crewed by his sons Charles and Toby. They are united by the need to find someone who matters to them - Olly is desperate to find his son Joe, Robby is searching for his brother Jan, and Charles his brother-in-law Alex. Unknown to Charles, he also has a stowaway...