Captain Sylvestre de Greybagges is your typical seventeenth-century Cambridge-educated lawyer turned Caribbean pirate, as comfortable debating the virtues of William Shakespeare, Isaac Newton, and compound interest as he is wielding a cutlass, needling archrival Henry Morgan, and parsing rum-soaked gossip for his next target. When a pepper monger's loose tongue lets out a rumor about a fleet loaded with silver, the Captain sets sail only to find himself in a close encounter of a very different kind.

After escaping with his sanity barely intact and his beard transformed an alarming bright...