The Tenth Power is the third novel in The Chanters of Tremaris Trilogy by author Kate Constable. In this novel, Calwyn, is a talented chanter from the city of Antaris on Tremaris. Calwyn is in the process of returning to Anatris with two of her friends in tow, after running away from the sisterhood a year earlier. Calwyn returns to the priestesses of Antaris because she has lost her powers from chanting. While Calwyn is hoping that her sisters to care for her and coddle her, she finds instead that the place she once called home is in great despair. The sisters hope that her return will save them and save their land.

Calwyn takes readers into the lives of the different groups of people that live on Tremaris, while she tries to regain her powers. The former High Priestess and the woman that is like a mother to Calwyn, Marna, tells Calwyn that there is a secret Tenth Power, and an object that holds the magic of this secret power. Marna dies before she is able to give Calwyn the details. Once Calwyn discovers the magic that Wheel Marna was talking about, Calwyn realizes that it is broken. The owner of the other half is her arch enemy, Samis.

Through her journey, Calwyn hunts for the other half of the Wheel. As the planet of Tremaris is deteriorating, Calwyn believes that putting the two pieces back together will save the planet, the city, and the chanters from the ill-fated snow-sickness.