A novel about a rose

Someone assassinates Jindřich, the Burgomaster of Bezděz, and the next day Oldřich of Chlum is accused by the royal chamberlain of embezzling money for the construction of the castle. Oldrich is forced to search under the guise of a common soldier, while his squire Ota is mistakenly captured, as his captors believe him to be the king's procurator. And she's forcing him to get married.