Who watches the Watchtower? In the wake of Absolute Power, the Justice League Unlimited has created a haven for all heroes — but can they keep it secure? Enter Renee Montoya, reeling from an abrupt end to her time in Gotham and looking for a place to hang her hat. But the Trinity didn’t bring her up to the Watchtower to relax — there's a dark threat bubbling underneath the surface, and only the Question and her ad hoc support team stand a chance of figuring out who the problem is before it's too late.