From Amazon Prime:

When wealthy philanthropist, Rachel Argyll, is murdered at her family estate, her adopted son Jack is arrested for her murder. He vehemently protests his guilt and eighteen months later, the identity of the murder is thrown in doubt. Now it is up to the rest of the family to decipher a killer amongst them.

From Amazon Prime you can stream the 3 episodes of this complete story. Each episode lasts about one hour.

Only at times did the drama seemed to drag a bit. But the plot and the characters are so well developed that we could not resist bingeing.  Have fun trying to spot the killer in this unhappy family in which the 5 children (all adopted) have all been mistreated by Rachel, their witch of a mother.

Several of the British actors may be familiar to you. Rachel, the murdered victim, is played by Anna Chancellor. Her husband Leo is played by  Bill Nighy.  Philip Durrant, the bitter son-in-law is played by Matthew Goode.

Included in the plot are one of the best pieces of revenge I have seen in a film.

For what it is worth, in the United States only Virginia prohibits the marriage of step-siblings.

If you are a fan of mystery soap operas, DO NOT MISS!