Patronisingly dismissed as "extras" by their glamorously gung-ho colleagues in the Paris police department, the city's Child Protection Unit must combine the skills of an empathetic child psychologist with the bluntest behaviour of a hardnosed law enforcer.
The emotional fall-out for a tightly-knit team that are more family than their own famille frequently rips apart marriages, destroys relationships and leaves troubled individual members looking to each other for support rather than their partners back home.
Director Maiwenn was inspired by a TV documentary and co-wrote the script after spending time with different CPUs, observing their coping mechanisms while dealing with some of the worst crimes society has to offer.
It may play out like a soap a le Bill with a bit of grit but this is not comfortably sudsy peak-time viewing: scenes include an induced foetus, the result of a rape, a smugly well-versed bourgeoise Parisian convinced he can sail away from an incest rap and scenes of a homeless woman forced to desert her young son.
The CPU members - all beautifully played with a convincing effortlessness by a cracking cast - range from the wise unit head to the female officer married to the job at the cost of her own to the seemingly stone-hearted femme whose cynicism colours every judgement.
The narrative takes a needless detour into a tentative romance between the photo-journalist "interned" with the unit and an emotionally explosive team member but - this aside - paints a compellingly authentic picture of the mentally gruelling life on the job.
Fans of police procedurals may find themselves aghast at some of the team's interviewing techniques - victims are quizzed and then asked to strip in open plan offices and - in one bleakly comic scene - a teenage girl is openly ridiculed for agreeing to sexual favours in return for her smartphone. "What do you do for a laptop?" one wag inquires.
Yet the gallows humour is absolutely essential for the CPU to function effectively, a truism brutally underlined by a turn of events that leaves the viewer emotionally winded.