The school holidays have arrived, and nine-year-old James can't wait to put his newfound skills to the test during the pirateers' annual Holus-Bolus Raid on the Cartagena Naval School for Laddies. But sneaking into the school isn't the only reason the Swashbucklin' Nay on Impossible Adventurers want to sail to Cartegena. Elizabeth, Emily, and James are determined to discover what happened to their father and the missing Phantom Lady. Meanwhile, Captain Bal has his own secret plans, Dani refuses to listen to Miss K's ominous warnings, and James keeps seeing mysterious shadows lurking in Cartagena's streets.

When the raid doesn't quite go as expected, the crew finds themselves carrying out their most dangerous Nay on Impossible mission yet: escaping from the mazelike dungeons of San Lazaro. Not to mention outsmarting the pirateer-hating guards, hiding from the furious Captain Silverbeard, plotting their revenge on the privies, and hunting for the next clue to the fabled Lost Treasure of Santa Maria—all before the Parade of the Pirates ends in three days' time.

Join the Joneses and the pirateers on their second hair-raising, humorous adventure as they are chased over rooftops, through tunnels, and seemingly across the sea itself by the one who wants to find James more than anything.