There are situations that fill even the most seasoned FBI K-9 handlers with shock and horror. Meg Jennings is preparing for another workday when she gets word of a catastrophic scene in downtown Washington, D.C. Part of a twelve-story condo building has collapsed, and the rest of the structure could soon follow. Every search-and-rescue worker and K-9 team is needed on-site immediately to find survivors--and assess the casualties.

Putting aside her fears for her firefighter fiancé, who's already inside the unstable building, Meg turns to the task at hand. If anyone is still alive within the rubble, she and Hawk, working alongside other K-9 teams, must find them. Every hour, every moment counts--and a wrong move could trigger a deadly chain reaction for those buried beneath. But beyond the present danger is a deeper threat, as evidence indicates that this wasn't a random tragedy, but an act of domestic terrorism. And identifying the culprit and the motivation, in time to stop another attack, means taking on an enemy with terrifying skills--and nothing left to lose.