Nina Borg, a Red Cross nurse, wife, and mother of two, is trying to live a quiet life. The last thing her husband wants is for her to go running off on another dangerous mission to save or protect illegal refugees. But when Nina's estranged friend Karin leaves Nina a key to a public locker in the Copenhagen train station and begs her to take care of its contents, Nina gets suckered into her most dangerous case yet.

Because inside the suitcase is a three-year-old boy: naked and drugged, but alive. Nina's natural instinct is to rescue the boy, but she knows the situation is risky. Is the boy a victim of child trafficking? Can he be turned over to authorities, or will they only return him to whoever sold him?

In an increasingly desperate trek across Denmark, Nina tries to figure out who the boy is, where he belongs, and who exactly is trying to hunt him down. Whoever put the boy in the suitcase put him there for a reason, and was not intending Nina to be the one to take him. When Karin is discovered brutally murdered, Nina realizes that her life and the boy's are in jeopardy, too.