Percy Jackson and the Olympians: Wrath of the Triple Goddess / Rick Riordan.

Enhanced descriptions from Syndetics:

In his continuing quest to earn college recommendation letters from the gods, Percy has to pet sit the goddess Hecate's polecat and giant mastiff during Halloween week. What could go wrong?

Rick Riordan's newest Percy Jackson adventure is full of hilarious set pieces, a diverse cast of gods and monsters, and many other delightful tricks and treats.

Percy Jackson, now a high school senior, needs three recommendation letters from the Greek gods in order to get into New Rome University. He earned his first one by retrieving Ganymede's chalice. Now the goddess Hecate has offered Percy another "opportunity"--all he has to do is pet sit her polecat, Gale, and mastiff, Hecuba, over Halloween week while she is away. Piece of cake, right?

Percy, Annabeth, and Grover settle into Hecate's seemingly endless mansion and start getting acquainted with the fussy, terrifying animals. The trio has been warned not to touch anything, but while Percy and Annabeth are out at school, Grover can't resist drinking a strawberry-flavored potion in the laboratory. It turns him into a giant frenzied goat, and after he rampages through the house, damaging everything in sight, and passes out, Gale and Hecuba escape. Now the friends have to find Hecate's pets and somehow restore the house, all before Hecate gets back on Saturday. It's going to take luck, demigod wiles, and some old and new friends to hunt down the animals and set things right again.

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Kirkus Book Review

With graduation on the horizon, Percy faces new challenges in this second series entry. It's October, a month for relishing the crisp air, changing leaves, and "pumpkin-spice burritos," when high school senior Percy is summoned to the principal's office to meet his aunt--a mysterious request for someone who doesn't have an aunt (at least, "not on the human side" of his family). The visitor turns out to be Hecate, the triple goddess of magic, crossroads, and necromancy. She insists that Percy petsit her hellhound and polecat while she's off enjoying Halloween festivities. Still needing two letters of recommendation if he's to join girlfriend Annabeth at New Rome University, Percy can't refuse. As always, Annabeth and Grover are happy to assist, and thus begins an autumnal adventure for the ages. Monstrous mayhem abounds, and characters from past adventures resurface. The localized focus of the action within New York City offers readers an insider's tour of locales such as Gramercy Park and the historically Greek enclave of Astoria. Reducing the geographical scale of the quests also allows Riordan to focus on Percy's maturation and introspection. This is arguably the most feminist novel of this universe: Percy reckons with several prominent women from ancient myth whose lives were ruined by men. One of the novel's most poignant vignettes involves Percy vicariously experiencing the anguish of the destruction of Troy through the psyche of one of its few female survivors. A superlative volume that combines strong characterization with thrilling action.(Fantasy. 9-14) Copyright (c) Kirkus Reviews, used with permission.