The novels of Patrick O'Brian are far richer the second and third time through.

The Surgeon's Mate, seventh book in the series, is nearly halfway done before O'Brian's famed captain, "Lucky Jack" Aubrey, sets foot on his own command, the British sloop Ariel. But never fear that the first half of the book is slow or lacking interest; it begins with Aubrey and his particular friend, ship's doctor Stephen Maturin, sailing as passengers into Halifax onboard HMS Shannon after its successful action against USS Chesapeake, a rare but decisive victory for the British navy against the Americans during the War of 1812. The celebration that follows is a treat.

Next follows a nail-biting passage back to England aboard a mail packet, closely pursued by a pair of mercenary American privateers.

And the reunion between Aubrey and his long-suffering wife, Sophie, is a touching scene rarely included -- or so richly developed -- in nautical fiction.

All's not well for Aubrey, either. A cunning businessman has taken advantage of his absence to advance questionable investments in his name, leaving Aubrey's former fortune in doubt. More pressing still is the imminent arrival of a lady from Halifax, who may bear the fruit of an indiscretion there and who might suppose she can supplant Aubrey's wife in his affections.

You can imagine, then, that Aubrey is only too eager to take command of a sloop, even if so small a ship is far beneath his station, in order to aid Maturin on a mission of great importance to British intelligence. Maturin, who returned to England bearing papers of great importance liberated from Boston in the previous volume, has stumbled upon some disturbing news while delivering (mumbling his way through) a scientific paper in Paris, and he needs none other than Aubrey to help him sort it out.

Of course, Maturin's own life is complicated by a complex romantic entanglement with the formidable Diana Villiers, no less than Aubrey's own cousin and a woman not easily won. And that's not even counting the pursuit in support of a British frigate through gale-tossed seas, or the rending crash off the coast of France, or their imprisonment in Paris....

The Surgeon's Mate certainly does not lack for plot. A lot happens in this book, and as always, O'Brian provides some of the liveliest dialogue, the most detailed nautical narrative and the punchiest action afloat.