Steeds of the Gods #3 (Beasts of Olympus);

Which mythical horse will win the race?
Beasts of Olympus is a series of illustrated chapter books set in a magical Ancient Greece where strange things still walk the Earth. In Steeds of the Gods, Demon, the official Olympian beast keeper, is caught between Helios and Poseidon, who are planning a race to see which of their steeds is the fastest. Both vengeful gods have requested Demon’s help, but he can choose only one.