There can be no murder in paradise, characters in Child 44 repeat at about twenty-minute intervals. The statement expands every time another person says it, indicating by turns their ignorance, brainwashing, or insurrection.
That's because the film (based on the novel by Tom Rob Smith) is set in the USSR during Stalin's reign of terror, and murderers lurk around the corner and in the highest echelons of government. The story follows Leo Demidov (Tom Hardy), war hero turned agent turned low-level enemy of the state and back again, as he investigates an apparent string of murders of children deemed “accidental” by authorities.
In the meantime, his relationship with his beautiful wife Raisa (Noomi Rapace) gets complicated when she reveals that their marriage isn't all he thought it was. But the murders keep happening, and the two of them are drawn into a partnership that puts them in danger.
It's hard to adapt a historical novel into a feature-length film; doing so successfully usually requires finding the soul of the story and then streamlining the action so it all points to the plot, stripping out B- and C-level plots that don't tie into the movie's biggest theme. Child 44 proclaims its theme from the start, in the movie's epigraph (yes, “there can be no murder in paradise”), but starts adding others, most notably Demidov's orphaned past and his struggle to locate a real father, which feeds, presumably, his desire to find out who is killing children.
There's also some critique of a regime that controls and reshapes truth through coercion. Also something about the beauty of nature versus the ugliness of forced labor. And then it jumps timelines, and cities ...1