Pirates of Darksea by Catherine Doyle

Max and his big brother Christopher have always shared their adventures. In fact for ages they’ve been sneaking down to Galway Bay at the turn of midnight, waiting for Captain O’Malley and his famed pirate ship to take them over the horizon to the magical world of Eighth Sea. Despite their messages, the Captain never arrived and now, two years later, Christopher is in grave danger. It’s not even the sort of danger Max can help with. Christopher is in hospital and getting sicker. Their parents want to take him far, far away for a new treatment, but they don’t have the money. That’s when a very loud, bright red parrot visits Max’s House in Bellflower Lane. Squawk is carrying a message from Captain O’Malley, who needs a new crew member to help with a top secret quest. The reward is treasure beyond Max’s wildest dreams.