The King's Questioner - Nikki Katz

From Nikki Katz, the author of The Midnight Dance , comes The King's Questioner, an epic YA fantasy featuring royal drama, dark magic, and a secret that could topple a kingdom.
Kalen is a mental picklock, able to access a person's memories and secrets by touch. His skills make him the perfect questioner to the king, and he spends his days interrogating prisoners of the crown.
But when Kalen's estranged childhood friend, Prince Cirrus, falls into a sudden coma, the king begs Kalen to intervene. By accessing Cirrus's mind, Kalen saves his life-and uncovers a terrifying secret. The prince has a sister, banished long ago, and she is the key to the destruction or survival of the kingdom.
With the help of Cirrus and a silver-haired thief named Luna, Kalen must find the princess and bring her home. Or risk death at the hands of his king.