The False Prince by Jennifer A. Nielsen (author) (US edition)

In a discontented kingdom, civil war is brewing. To unify the divided people, Conner, a nobleman of the court, devises a cunning plan. He will find an impersonator of the king’s long-lost son and install him as a puppet prince. Four orphans are recruited to compete for the role, including a defiant boy named Sage. Sage knows that Conner’s motives are more than questionable, yet his life balances on a sword’s point. He must be chosen to play the prince, or he will certainly be killed. But as Sage moves from a rundown orphanage to the king’s sumptuous palace, layer upon layer of treachery and deceit unfold. Until, finally, a truth is revealed that may prove more dangerous than all of the lies taken together…