Brotherband: The Caldera by John Flanagan fictional adventure book. This book has many viking like features and is a companion series of Rangers Apprentice. It is the 7th book in the series; Brotherband. The brotherband is a group of young vikings. The brotherband consists of Hal, the skirl of the Heron (the boat he captains, Stig, the first mate, Ulf and Wulf, the identical twins, Edvin, an average person but he is the cook and healer of the group, Ingvar the big muscular person, Jesper the former thief, Stefan, the joker of the group but can mimic sounds, Thorn the battle trainer and elder of the group as he is more experienced and older, Lydia, the only female in the group and uses an atlatl, and then there's Kloof, Hal's dog. In this book Stig's dad comes back after leaving 15 years ago. His dad, Olaf, needs a crew and ship as he was blamed for the Byzantos empress's son was abducted by some pirates. The crew accept the mission. They go island to island ...