Throne of Glass

Why these tropes fit

A lethal assassin competes in a deadly royal tournament to win her freedom, then leads an urgent quest to unmask and stop a murderous force hiding within the castle.

Evidence from the source

• Quest: “a desperate quest to root out the evil before it destroys her world.” source
• Strong Heroine: “When her competitors start dying mysteriously, one by one, Celaena’s fight for freedom becomes a fight for survival—and a desperate quest to root out the evil before it destroys her world.” source
• Tournament: “If she defeats twenty-three murderers, thieves, and warriors in a competition, she will be released from prison to serve as the King’s Champion.” source

Metadata source: Open Library. Quotes are used only to verify the tags.