Biggles plan to keep the submarine away from the island is thwarted by the refusal of the Jamaican government officials to give him the bombs he needs. Algy pleads with the minister's secretary, but already it's too late for him to join Biggles by nightfall. Just before dusk, Biggles sees the submarine surface not far away, and unless the plane comes with the bombs, nothing can prevent it from joining the yacht...