Several families have met together to have a picnic on a pleasant local beach. To everyone's delight they are joined by Harry Merryweather, a midshipman home on leave. Harry and another youth, David Moreton, go for a wander round the rocks, but are cut off by the strong tide. The weather then turns very nasty, but the boys are able to swim to a passing boat containing an old man, Jefferies, and his young grandson, Tristram. The weather is now so bad they can't get back to the local harbour at Penmore. There is an accident and young Tristram is lost overboard, and drowned.