The Invaders by John Flanagan
When Hal and the Heron Brotherband fail to protect the Skandians' most prized possesion, the Andomal, they set off to track down the pirate who stole it to redeem themselves. They cannot return without it, or they will be punished. But a fierce storm comes up and they are forced to stop their search. While they wait, they train for their encounter with the pirates.
When the storm finally lets up, they track the pirate to a nearby village. With some unexpected help, can they liberate the village and get their prize back?
**Book 2 in The Brotherband Chronicles**
Previous book: The Outcasts
Next book: The Hunters