When a senior captain is injured, Captain Charles Mullins is given temporary command of HMS Centaur for a brief period. When the former captain becomes implicated in an embarrassing scandal, Mullins remains in command longer than expected.
After Moorish pirates take an East India Company ship, Centaur sails to North Africa to rescue the ship, passengers and crew.
Later Captain Mullins takes his ship to the North Sea where he is ordered to capture an enemy island that may to be used for launching an invasion of the Caribbean.