Soon after getting married, Hornblower is sent on a search and rescue mission for a British ship (under the command of an old friend) last reported off the French coast. In the midst of the search, the HMS Hotspur picks up some unwanted passengers and attempts to discover the objective of a small French invasion force.

Finally promoted to Captain and given command of HMS Hotspur, Hornblower is sent to France to determine the status of Napoleon's pledge of peace, but instead he discovers Napoleon's troops waiting to invade. He also begins a romantic relationship with the young Maria Mason.