Captain Barracuda is obsessed with finding the treasure of Phineas Crane — the most valuable treasure in the Caribbean. To achieve this, he enlists the help of Spark, a young girl pretending to be a boy in order to fit in with Barracuda’s savage pirate crew. The discovery of Phineas Crane’s book of memories will be key to finding the treasure and saving Spark, because she is the only person on the ship who can read the “map of letters” that is the manuscript.