Percy Jackson has saved the world multiple times – battling monsters, Titans, even death himself – so graduating high school should be a breeze, right?

Wrong. Percy needs three recommendation letters from the gods before his final year in high school comes to an end. And one thing Percy knows, the gods on Mount Olympus don’t do anything for free.

To secure his second letter, Percy and his friends Annabeth and Grover agree to a new quest – pet-sitting for the goddess Hecate while she’s away over Halloween. They just need to follow her simple rules:

• Look after the pets like their lives depend on it (because they do)
  
• Don’t touch anything – especially Hecate’s magic potions!
  
• See points 1 and 2

But when Grover’s curiosity gets the better of him, the trio find themselves with a giant goat, a destroyed house, and Hecate’s (terrifying and potentially deadly) pets on the loose in New York City.

Now the trio have twenty-four hours to find the pets and restore the mansion to order – or face the full fury of Hecate and her horrifying three-heads.