Helping Hercules by Francesca Simon
Here are the Greek myths as you've never heard them before.
Susan is whisked back through time to Ancient Greece, and finds that helping Hercules clean the Augean stables is much, much worse than tidying her room. One hair-raising experience follows another as she goes down into the Underworld with Orpheus, just misses being turned to stone by Medusa, and rides on the winged horse Pegasus.
This is both a fabulously funny story and a brilliant way to introduce children to eight of the best-known Greek myths. Susan meddles in each of the myths - taking a dim view of the gods and goddesses and heroes she encounters - but gets out in the nick of time, so the myths themselves remain unchanged and will be remembered vividly by their readers. To make it easy, there is even a guide to pronouncing Greek names.