Two detectives from opposite sides of the U.S.-Mexican border work together to track down a serial killer when a body is found on a bridge connecting Texas and Mexico.

Marco and Sonya investigate the body from the bridge, Frye learns that the killer isn't done with him, and Charlotte makes an unwelcome discovery on her property.

Sonya and Marco race to track down a prime suspect who could lead them to the lone desert survivor. Charlotte confronts an unexpected visitor determined to keep business as usual.

The clock ticks as Maria's broadcast continues. Sonya searches for the girl's location. Against protocol, Marco works a unique ransom angle. A powerful Juarez force crosses the border.

Sonya and Marco suspect a cover-up, Charlotte goes to Marco for advice, a troubled girl seeks adventure in Juarez and a visitor stops by Linder's apartment.

Sonya bonds with a key witness from the case, Marco uncovers Sonya and Hank's past and Charlotte calls on an old friend for help.