This audiobook is by Rick Riordan and is narrated by Jesse Bernstein and in this story Grover locates two other half-bloods who are twins.

So, Percy, Annabeth, and Thalia are sent to this school that the twins are enrolled in to take them to Camp, Half-Blood but things don’t go as planned and Bianca who is one of the twins chooses to join Artemis’s, all girls group called The Hunt.

There is also another mission that Percy doesn’t get though he ends up getting involved in it anyway. As his friend Annabeth has been captured.