Brown, Rina "Truth at Sea" Book 3 of Isle of Dark Series

A time of peace has settled over the land. Guardian's are able to enjoy life as never before. Even Ranger is thinking about setting his sword aside and embracing happiness. Having no memory of his previous life, Isle has fully embraced being Ranger's adopted son, and has every intention of being the best Datsoe hunter in the land.
When Queen Francine once again calls upon her most trusted warriors to find pirates terrorizing the seas, they set off for
Seaburné to investigate. Isle is struck by the beauty of the town, but he can't shake the feeling that he has been there before. Joined by the courageous Captain of The Vengeful Voyager, they set sail on a perilous journey to discover who is in charge of the band of thieves attacking unsuspecting ships.
Filled with Juduiverian secrets, ancient artifacts, and treasure, Ranger and Isle's journey will bring them face to face with Isle's lost past, and the truth will shock them all.
In this third installment of the "Isle of the Dark" series, the beloved teen Datsoe's life will be changed forever.