Overdue

Our hero, the 17-year-old midshipman of the Salamis, is suddenly given the job of going aboard and taking command of the Mercury, an emigrant ship that they find drifting in mid-ocean, all her officers having died in various accidents, and the illiterate bosun and the ship's carpenter knowing full well that they had no idea how to navigate. He takes charge and all appears to be going well, when-- But I will not spoil a good story for you.