Warning: contains finale spoilers forTowards Zero.Why have a husband when you can have a lawyer? asks Lady Tressilian in episode one ofTowards Zero. Its a maxim that Audrey Strange would have done well to follow, considering how this twisted story unfurled.The name Nevile Strange with its idiosyncratic one-l spelling was a clue hiding in plain sight thatTowards Zeros handsome tennis star was no hero, but an evil stranger (indeed, in Agatha Christies 1944 novel on which this three-parter is based, Nevile isnt even a blood relative of the Tressilian family but Sir Matthews ward who grew up with them under an assumed identity after committing a childhood murder).A cold-hearted psychopath who saw everything as a contest and who couldnt stand to lose, Nevile very nearly succeeded in having Audrey hanged for his aunts murder. In fact,hewas the one whod bashed in her ladyships skull and smothered family lawyer Mr Treves with a pillow two more killings to add to that of young Peter James, a child shot dead by Nevile as a boy, using a bow and arrow as a boy. Thanks to Inspector Leach, Neviles plan was scuppered and he was sent to the gallows, ridding his family of a foul canker. Heres how it all played out.Why Did Nevile Try to Frame Audrey?To punish her. An obsessively competitive man, Nevile felt that Audrey had publicly humiliated him when she sued for divorce on the grounds of adultery. He had been a serial philanderer throughout their marriage, but Audrey had suffered in silence until he began an affair with Kay Elliott. Finally deciding to act, Audrey stole Kays monogrammed compact and planted it in Neviles car as evidence of the adultery, which forced him to publicly confess and to grant her a divorce.Nevile pretended to feel remorse for his behaviour and to want to stay friends with Audrey, when in reality he was seething with resentment and planning her downfall. He married Kay, whom he never loved, and arranged to spend their honeymoon at Gulls Point when he knew that Audrey who had also grown up there as a ward of his lord and ladyship would also be visiting. There, he carried out his plan to kill Lady Tressilian and to frame Audrey for her murder in an act of revenge.Kay and Louis Secret PastNeviles second wife Kay, somewhat incidentally, was revealed along the way to have been a con-artist who, along with her rakish paramour Louis Morel, preyed on the wealthy. She had first approached Nevile Strange at a tennis match in the South of France intending him as one of her marks, but then betrayed Louis by falling for Strange and his luxurious lifestyle and choosing to stay with him. That explains the tension between Kay and Louis when the gang spend the afternoon dancing at the Easterhead hotel where Louis is staying.Trying to make Thomas Royde jealous, Mary later invites Louis to Gulls Point, making Nevile, Audrey and Kays love triangle a love square. After Neviles arrest, Kay and Louis are seen driving away together, reunited, and now its unclear perhaps having inherited Neviles money, inadvertently making him the ultimate mark of all.Mac the Illegitimate SonWhen Nevile Stranges new valet Mac (real name Matthew Hutton) sized up his employers clothing against himself, it looked as though he were plotting to usurp Neviles position. Was he in cahoots with Kay, as it seemed when they shared a sip of whisky from the same hip flask? No. Hutton was simply comparing his and Neviles shoesizes and more to spot a family resemblance because they were cousins. Unlike the book, in which there is no Mac character, and Nevile is not a blood relation of Sir Matthew Tressilian, in the TV adaptation Nevile is Sir Matthews nephew and Matthew Hutton is Sir Matthews illegitimate son.Matthew (clearly named after his biological father) was the product of a liaison between Sir Matthew Tressilian and a 16-year-old scullery maid. When Lady Tressilian found out about the pregnancy, she sent the maid away and kept it as a family secret explaining why she watched Sir Matthew drown without alerting any help, told Inspector Leach that its a terrible thing to be angry at the dead, and smashed her husbands framed photograph.Nevile hadnt factored in Mac/Matthew Huttons role when he killed his aunt to frame Audrey. Because Hutton was wrongly arrested for her ladyships murder, Nevile was forced to commit another murder that of Mr Treves while Hutton was in police custody, in order to incriminate Audrey.Join our mailing listGet the best of Den of Geek delivered right to your inbox!With Nevile hanged, did Mac inherit his fathers house in the end? Despite noting that bastards cant inherit, he is seen packing the place up at the end of the three-parter, so perhaps he did end up with Gulls Point? As for Audrey, she left the place behind, finally free of Neviles psychological torment and the starvation of their relationship.Mary and ThomasNot involved in either of the Gulls Point murders, ladys companion Mary and cousin Thomas were each rewarded by substantial payments from Lady Tressilians will, freeing them up to leave Salt Creek and become independent. Mary told Thomas that she planned to use her money to travel, first on le train bleu to Nice and then on the Orient Express (the setting for one of Agatha Christies most famous Hercule Poirot novels).Thomas now had the money he needed to return to his Malaysian rubber plant, and sets off there but promises to keep up his and Marys correspondence, hinting that the couples path may cross in future too.The Murder of Young Peter JamesIn the novel, it isnt explicitly revealed that young Nevile Strange was Peter James killer, but all the ingredients are there for the reader to work it out. In the book, Mr Treves tells the story of a child killed by another child using a bow and arrow, and says that the killer was sent away and raised under a new identity. The murderer, says Treves, had a certain physical peculiarity that would mean they could be correctly identified even in adulthood. Treves is telling the story as a warning because he has recognised just that physical peculiarity among the guests at Gulls Point (Nevile Strange has a shortened finger on one hand, which we assume is the peculiarity) and is trying to warn Nevile that hes onto him. In the TV adaptation, its made much clearer that Nevile killed Peter but owned up to it and pretended that the murder was a tragic accident, which Thomas Royde knows to be a lie.Inspector Leach, Sylvia and BarrettThree lonely souls were united at the end ofTowards Zerowhen the previously suicidal Inspector Leach, whod suffered with PTSD and survivors guilt after World War One, offered to become the ward of orphan Sylvia, whose previous guardian Mr Treves had been murdered by Nevile Strange.Joining them will be Mrs Barrett, the housekeeper at Gulls Point now in need of work following her ladyships murder. Leach and Barrett shared a tender moment when he expressed shame for having led men like her son to their deaths in the war, and guilt for having returned alive when so many of them did not. Barrett wisely told him that his death wouldnt have kept her son alive, and not to carry the guilt. The three of them will now form another ersatz Salt Creek family, but hopefully a less viperous and much happier one than lived at Gulls Point.Inspector Leach doesnt feature in Agatha Christies 1944 novel Towards Zero, but is instead a composite based on three characters in that book: (1) Superintendent Battle, who investigates the murder at Gulls Point with his local bobby nephew (2) James Leach while on holiday where Leach is posted, and (3) Angus MacWhirter, a guest at the Easterhead hotel who attempted to take his own life a year before the events of the novel. The Sylvia of the novel is not an orphan and Mr Treves ward, but the daughter of Superintendent Battle. In the book, when Sylvia confesses to thefts that she didnt commit at school, it inspires Battle to realise that Nevile was the true culprit all along.All episodes of Towards Zero are available to stream now on BBC iPlayer.