Mary O'Sullivan is out of her depth, and out for blood. With her headquarters buried in rock, her resources are scarce. But Mary needs to stop the vengeful alien demi-god, Sever, before he murders the man she loves—and before his prison of a forcefield spreads around the globe. But saving the world isn't a solo business, and Mary—along with the whole league—will need to let go of her past grudges if she wants to rescue the future. Defender is the concluding volume in the League of Independent Operatives superhero saga.