When Luisa Herrera, a former intern at the Lyell Centre, is killed in a car-jacking in her native Mexico Nikki arrives for the funeral, only to find that the body in the coffin is not Luisa's. She seeks out Luisa's boss, Dr Eva Vasquez, who runs a charitable hospital, also a centre for a dedicated band who search for families abducted by drug cartels as the police are too afraid to. Luisa was one of that group. Jack flies out to assist Nikki look for her friend, unearthing the bodies of several torture victims but chief suspect El Buitre refuses to give any information even when Nikki withholds his medication. Eva's son Ernesto is also kidnapped and Eva and Nikki, following a tip-off, go to find him. However Jack discovers Eva's car with Eva inside but no Nikki.

Frantic to find Nikki, who has been buried alive, Jack gets a mysterious phone call allowing him to ring Nikki and another call demanding a ransom and the release of cartel member El Buitre but the exchange goes wrong. Helped by Luisa's lover Gustavo Jack is able to locate and free other abductees from their underground prison, including Luisa herself and Eva's son Ernesto but Nikki is not with them. Ultimately Nikki draws on the lessons she learned from former mentor Leo to try and free herself whilst Jack discovers that she has been the victim of a desperate arrangement.