SECRET OF THE RAVENS HC GN (9780358629443)

Twin siblings Elliot and Liza only have each other. Their parents are gone. Their home was taken, and to survive on their own, they're forced to scrounge up plastic and metal to trade for coin within an abandoned garbage heap. Desperate to escape the vagabond cycle that they're trapped in, the answer to their plight seemingly appears when they stumble upon a Raven Quest-magical tasks offered by mysterious message-carrying ravens that when successfully completed, promise the victors coin and untold riches.
In a gamble to change their fates, Elliot and Liza follow the trail of Raven Quests to the kingdom's capital, where the greedy rulers of the Kawumiti Kingdom reign and young people are enlisted to train as royal mages for the kingdom's army. But the Ravens Quests aren't as they seem, and the King is on a mission to hunt down vagrant participants like the twins. When a quest goes terribly wrong, Liza is poisoned, and Elliot finds himself racing against the clock to find the cure. Now, the only way to save his sister is to join forces with a royal apprentice and a dark mage with mysterious motives of her own-even if it means sacrificing everything.