A mother with mental disorders remains alone with her parents and two children in a country house. At night they are all killed, the house is locked from the inside, and the police believe that she committed the murders, but in the end it turns out that this is not the case, and the killer was able to get out of the house thanks to the kitchen window, which was closed from the inside with a strong blow
That sounds not unlike the real life Jeremy Bamber case, recently dramatized by ITV in the UK as White House Farm ( https://en.m.wikipedia.org/wiki/White_House_Farm_(TV_series ).
Also known as The Murders At White House Farm (2020) https://www.imdb.com/title/tt11110622/
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