Meg and Hawk are part of the FBI's elite K-9 unit. Hawk can sniff out bodies anywhere - living or dead - whether it's tracking a criminal or finding a missing person. When a bomb rips apart a government building on the National Mall in Washington, D.C., it takes all of the team's extensive search-and-rescue training to locate and save the workers and visitors buried beneath the rubble.

When a young girl is found dead in the mountains outside Timber Creek, lifelong resident Officer Mattie Cobb and her partner, K-9 police dog Robo, are assigned to the case that has rocked the small Colorado town. With the help of Cole Walker, a local veterinarian and single father, Mattie and Robo must track down the truth before it claims another victim. But the more Mattie investigates, the more she realizes how many secrets her town holds. And the key may be Cole's daughter, who knows more than she's saying.

Crack CIA analyst Trista Gold is a whiz with the computer, but not so much with people. She hides behind her job, analyzing top-secret code and making recommendations on national security. CIA K-9 officer Sgt. Matt Connors suspects that beneath Trista's uptight appearance, there's a sexy woman itching to cut loose. But he doesn't dare act on his attraction. He's a loner and always will be. Keeping away from Trista is a must-do directive. Until he doesn't have a choice. During a routine assignment, Trista stumbles across a cryptic exchange. Then someone tries to murder her - twice.

After a tragic loss, Jessica Chamberlain changes jobs, moves, and adopts a rowdy German shepherd. The two begin training with a Virginia search-and-rescue group. The group's training director, Nathan Tanner, is a former military working dog handler with scars of his own and he quickly picks up on Jess's ongoing anxiety. After the unexpected discovery of a body in the woods, Jess and her dog and Nate are drawn into the FBI's search for an abductor targeting women. Tormented by her past and terrified of the future, Jess still forges ahead.

It should have been a routine investigation. Instead, DEA K-9 agent Adam "Deck" Decker watches in horror as one Denver hospital seems to be ground zero for overdoses of a new drug. Now Deck can only hope a certain ER doctor will help him and his canine partner track down the source. Dr. Tori Sampson has her reasons for not trusting federal agents, especially ones working for the DEA. But the rash of overdoses—including a heartbreaking case involving a teen—is alarmingly high. And the new opioid is not only extremely dangerous, it defies all the usual medical treatments.