Royal poisoner

The Royal Poisoner is the first of the three books of the Kingfontaine series (a million copies were sold, the series is a bestseller Wall Street Journal).
King Severn Argentayn is surrounded by sinister fame: he usurped the throne, destroyed direct heirs, does not spare dissenters. The Duke of Kiscaddon decided to oppose the king and lost. Now the Duke of Kiscaddon is forced to send his youngest son Owen to the king’s palace as a hostage. The life of the son will depend on the loyalty of the father.
Trying to find friends and slip away from the ubiquitous spies of North, Owen learns to survive at court. But when new evidence of his father’s guilt appears, which threaten with death and Owen, Owen has no other way out, except to win the king’s favor - any, even in the most ridiculous way. And only one single person can help Owen in his almost hopeless business: a mysterious woman hiding in the palace and who has real power over life, death and rock