The Medusa protocol

"Mark's protege Astrid has been kidnapped and is being held in a mysterious prison on a remote island off the coast of Brazil. Can she escape while keeping her pledge to not to take another life? When Astrid, known in her elite assassin days as Azrael, stopped showing up to Assassins Anonymous, the group assumed her past had caught up with her. Only Mark, Astrid's sponsor and formerly the deadliest assassin in the world, holds out hope that she's...