The fifth episode in Shetland Season 10 came with a string of revelations and shocking confessions that deepen the mystery of Eadie Tulloch's murder. While DI Alison "Tosh" McIntosh struggles to uncover the real killer, she realizes that her co-worker Billy McCabe might be related to the mystery.The official synopsis for Shetland Season 10 Episode 5 reads as follows:Tosh finally confronts Billy about his relationship with Robert Tulloch. Fuelled by guilt over Louden, Calder goes after the people responsible.On the other hand, DI Ruth Calder feels responsible for Will Louden's condition, who was found unconscious after an overdose and is now in a coma. Ruth vows to uncover the secrets behind the dr*g ring in Shetland.Here is what went down in Shetland Season 10 Episode 5.Shetland Season 10 Episode 5 recap: Tosh investigates Eadie's murderShetland Season 10 Episode 5 continued Tosh's investigation into Eadie's murder and she shares her suspicions with Billy. Tosh believes that Robert Tulloch was corrupt and as Gina Powell revealed, he was likely taking bribes and framing suspects in his wife's murder. Things get tense when Tosh discovers a missing bank statement about an outgoing payment of 10,000 pounds from Robert to Billy in 2001. While Billy claims the money was for a loan for his house, Tosh suspects him and asks him to stay out of the station till she has cleared the investigation. Billy is upset and maintains that he has helped Tosh on multiple occasions.Elsewhere, Tosh arrests Tom on suspicion of Eadie's murder after his footprints were found in her kitchen. While Tom initially denied being in Eadie's house, he eventually accepts that he went to the deceased's house to confront her about the baby's adoption. While Tosh believes that Tom had a solid motive for murder, as Eadie was meddling in his family affairs behind his back, he is eventually released.Shetland Season 10 Episode 5 recap: Billy comes clean to Tosh View this post on Instagram Instagram PostAfter Tom is let go in Shetland Season 10 Episode 5. Tosh and Ruth meet with Colin Waite, who discovered Eadie's body. After Ruth reveals that Colin's mother and Eadie were arch-enemies, Tosh questions Colin but he maintains that he has nothing to do with Eadie's murder. In fact, after his mother's death, Eadie had been supporting and regularly checked on him like a mother.Elsewhere in Shetland Season 10 Episode 5, Billy checks the missing bank statements for Robert and decides to come clean to Tosh. He reveals how Billy and Robert were alone at the station when a storm hit their neighbouring village twenty years ago. Things got tense when Robert received a phone call about Craig and Ally, who went out on a boat and never returned. While Robert and Billy did not find any bodies in the washed-up boat, they discovered kilos of heroin. However, since Robert did not want to make the matter public and trouble the villagers, he promised Billy that he would take care of the dr*gs. Billy suspects that Robert Tulloch misused this situation and he was afraid of getting caught up in the mess. Tosh expresses her disappointment with Billy and regrets that Will and others could have been saved if Billy had reported the dr*gs twenty years ago.Shetland Season 10 Episode 5 recap: Ruth wrestles with guiltRuth's spiral over Will Louden's condition deepened in Shetland Season 10 Episode 5 and she promised to do justice by him. While Will fights for his life in the hospital, Ruth is convinced that his overdose was not self-inflicted. His friends and roommates even maintain that Will was clean for months. Ruth discovers that Will received a phone call from someone named Lewis Mitchell and orders Sandy to search for him.Back at her home, Ruth confesses to Ed that she feels responsible for Will's condition. She first caught him while he was shoplifting perfume from a mall. After Ruth discovered that Will was on parole and had a history of dr*g abuse, she saw an opportunity to turn his life around but he ended up in a hospital.In the final moments of Shetland Season 10 Episode 5, Sandy finally finds Lewis Mitchell with dr*gs, a ton of money and Will's phone. While Sandy accuses Lewis of Will's condition, he reveals that the Callaghans are the masterminds and promises to take the authorities to his boss. The episode ends as Sandy tries to reach Ruth but she does not answer her phone.For the latest scoops on your favorite TV shows and movies, follow SoapCentral.