A Sprinkle of Sorcery — Michelle Harrison

In this sequel to A Pinch of Magic, the three sisters face a haunted shipwreck, a fierce pirate, and, of course, a little magic!

The Widdershin family curse has been lifted, and the three sisters -- Betty, Fliss, and Charlie -- are free to leave the misty prison isle of Crowstone. But when a mysterious girl arrives at their inn accompanied by a will-o'-the-wisp, or ghost, it seems another adventure is afoot. The stranger, named Willow, is an escaped prisoner from nearby Lament, desperate to clear her father's name before he's executed for a crime he didn't commit. 

Then Charlie is kidnapped by poachers, swept away on a dangerous mission in search of pirate treasure that's protected by a vengeful ghost. Betty, Fliss, and Willow pile into their trusty boat and embark on a journey to a mythic island that exists only in legends.