Rampage! - Julia Wills

Madcap, modern yet mythological adventure!Aries, the ghost of the ram of Golden Fleece fame, is feeling slighted that no one sees him as a real hero, even though on his first quest to Earth he thwarted wicked sorceress Medea. But Medea is plotting again, in the rainforests of the fabled land of El Dorado, and goddess Athena wants Aries and his best friend Alex, zookeeper of the Underworld, to stop her. But this time a 'professional hero' is being sent with them - none other than Aries' arch-nemesis, Jason!
Things are worse than they know, however. Their friend Rose is in the Amazon too, searching for her lost father, and Medea needs Rose's help to restore her powers and wreak revenge, not only on Earth but also in the Underworld . . . and Medea knows just how to manipulate Rose into doing it.
Filled with laugh-out-loud humour, magic and mayhem, this courageous quest pits classic Greek myth and heroism against a modern world full of danger, and the deceptions lurking deep in the heart of the dark jungle.