Pégase, tome 4
Kate O'Hearn2012

A deadly plague is causing the Olympians to fade one by one.As Emily watches Pegasus slip away she is determined to save him and embarks on a quest that takes her back in time to the deadly war between the Olympians and the Titans.
In the race to save Pegasus, will Olympus find its true Hero? it's time for the original battle to be fought once again...

Titre original : Pegasus, book 4: Pegasus and the origins of Olympus (2012)