"The Circle Opens" is a series of four fantasy novels by Tamora Pierce, set in the same universe as her earlier works. The story follows a group of young mages, each with unique magical abilities, as they navigate their personal growth and face various challenges. The series emphasizes themes of friendship, responsibility, and the importance of understanding one's powers. The main characters include Daja, Sandry, Tris, and Briar, who each come from different backgrounds and cultures. Together, they learn to harness their magic while dealing with external threats and personal dilemmas. The series highlights the significance of collaboration and the bonds formed through shared experiences.