Niall Deeley is a character appearing in the episode Harvest of Souls of the ITV crime drama Midsomer Murders.
Niall Deeley was the result of an affair between Butch Nevins and Serena Harris during the 1979 harvest festival held in Whitcombe Mallet. He was born in 1980, though wanting to keep their reputation intact, Jasper Wyham, who had just married Serena, told everyone - including Butch - that the baby was stillborn while they secretly gave him away for adoption. When the boy became older, Niall married Rowena Deeley and together, they operated a pub in the area called the Black Dog that saw a peak number of visitors during the autumn festival and there, they they sold a special kind of organic beer exclusively brewed for the place named Midsomer Nectar - a favorite drink of Wyham stable manager Rod Barkham. However, life was very unfair for the Deeleys as the two managed to have an unnamed daughter, though was either born or inflicted with some sort of terminal illness that required an emergency kidney transplant to save her life. Rowena contacted her parents, though because Niall never met his Mom or Dad, he had to write through the adoption agency to get a response and because neither of them responded, Niall had to watch his child get sicker and sicker until sweet release. The Black Dog was the only thing they had left, though running it proved to be a real challenge as despite pouring every penny they could into the place, it was on the verge of collapsing. Niall desperately fought to keep the pub afloat, though behind his back, Rowena was looking for greener pastures as she considered selling it to Harry Wyham - a regular who had been trying to evict the entire Whitcombe village as part of his real estate plans. On top of that, they had a horse named Lightning that meant a lot to them. However, Lightning was loaned to the Wyham's as part of a stabling fee and they fell behind on paying the rent, he effectively repossesed their steed.
Some time before the events of Harvest of Souls, Niall figures out who his parents were and the family they started after abandoning him. Overcome with anger and sadness, Niall begins a quest of revenge on his Mom and Dad, along with anyone who stands in his way, as we first see him walking in on an argument between Harry and Rowena about selling the pub when Deeley asks what he wants as Wyham asks for a pint. Niall gives it to him, although unbeknownst to Harry, Delley laced it with a supply of ketamine he somehow acquired from the veterenarian centre and is consumed with his drink. Later that night, Deeley makes his way to the Wyham equestrian stable where he waits for Harry to come back, his vision getting blurrier and distorted as the last thing he sees is one of the horse pens being unlocked before he collapses to the ground - dying on the spot. Niall drags his lifeless body into the pen and locks it shut, then pulling out a gun that he fires up into the ceiling; triggering the horse to trample Harry's dead body numerous times to make it look like an accident. The motive for killing him was that he was the eldest son of his mother Serena, who gave him away in the first place and never responded to the emergency letter he sent to the Wyham's about his daughter.
The next day, the police are led to the Black Dog when Niall comes up to tell Rowena that Harry is dead - without mentioning that he was responsible. Interviewed by DCI Barnaby and DS Nelson, he mentions to them of Harry's exploits in trying to buy out the pub for real estate and that he made a threat to Butch just the other day. The next night, as the Nevin's begin their second Wheel of Death stunt show for the evening, Niall makes his way undetected in the audience as he hides beneath the curtains and pulls out his pistol, with a silencer attached - aiming for both Butch and Dale while not making a sound. Though noticing a lights operator returning to the post he choose to kill from, Niall is forced to retreat and improvise his plans - but not before planting the gun underneath the Ghost Train attraction to frame Butch's youngest son Sean, as he had an argument/fight with Harry before he died. A few days after some horses are stolen from the Wyham stable, Barnaby and Nelson find out they used to own a horse as they confront the Deeley's on this. Niall confirms being the owner of Lightning, though its here that he finds out Rowena wanted to sell the Black Dog behind his back, despite agreeing not to. As soon as the detectives leave, Niall gets into an argument with Rowena over the pub as he states they can find a way out of their financial woes while she wants to move elsewhere and that she found a doctor who thinks she has a chance at raising another child. Triggered with PTSD over what happened with their first episode in "parenting," Niall says he can't go through that again and storms off on her. On that night, Niall breaks into the veterenarian centre to lure its manager, Clara Myerscough, into a trap where he stuns her in the neck with a cattle prod and drags her into an equine spa where he cranks the hydro, pump and blow knobs to maximum as water slowly rises around her; drowning the veterenarian to death. The motive for killing Clara was that she knew of Butch and Serena having an illegitimate child, though always assumed it was stillborn before the events of the episode and somehow found out the truth before her death (its never specified when and how exactly this happened though).
The next day when the horses are retrieved by the police, Barnaby and Nelson notice that Lightning is the only steed taken during the heist that was not found at the campsite and they confront the Neeleys on if they took matters into their own hands to take her back. He says that he was at the pub all morning selling beer to customers and confirms thtat he does sell Midsomer Nectar - the type of beer that was found at the robber's campsite. However, while this might be just a theory, its possible that Lightning was the horse used to trample Harry to death as teh police are seen taking it away with blood-stained hooves, though was said to have been stolen along with the rest of the Wyham's livestock. Its possible that Niall found where the horses were being kept and retrieved her before the police found the horse box - either keeping it locked up or selling it away so police wouldn't tie it to him being the nurderer. Later that night, Niall breaks into the Nevins Wall of Death showtime and kills Dale by knocking him off his motorbike and runs a wooden carnival pole through his chest; impaling him as he bleeds out. The motive for murder was that Dale was the eldest son of Butch who was never notified about Niall's daughter needing a kidney transplant and even if he was, was too busy getting women pregnant to be bothered to do anything about it.
The next morning, Niall prepares the final stage in his roaring rampage where he summons Butch to the Black Dog for a drink to explain what he wants to talk about when he gets a call from Serena that Amy Wyham is missing and asks if Rowena is there. Unbeknownst to him, Deeley snuck out on him when he was serving customers as part of a kidnapping conspiracy by Jessica Myerscough. Using the opportunity to kill two birds with one stone, Niall invites her to the pub to help look for Rowena when Butch denies another drink so he can head back outside. Unfortunately for him, Niall locked the door as he swings a fire poker at his head while calling him "Dad" out loud. As soon as Serena knocks on the front door, Niall opens it as she lures her closer inside while holding the poker behind his back. She tries to turn back as soon as she sees Butch wounded and tied up, though Niall orders her against the wall as he threateningly declares them "one big happy family" while wondering for so long about the day his parents would find out what they did to the son they abandoned. Deeley realizes that Serena never told Butch about their son being given up for adoption and that she lied about him being stillborn, along with blaming them for the death of his child since she failed to give Butch the letter; as well as calling him out for his infidelity while wondering how much other illegitimate children he's got around Midsomer. Upon realizing Barnaby and Nelson snuck their way in through the back, he warns them not to come any closer and that he must finish this. When Barnaby assumes this was all about his daughter, Niall tells him he already explained how her death was unavoidable and that they needed to feel the same pain he felt - by killing the eldest child of each parent (Harry and Dale). When asked about Clara, he states he hated killing her as a friend, though was necessary to cover his tracks after she told him she knew everything about him. Barnaby states that it must end now, though Niall screams he has no idea of all the pain that's manifested in him over the years. Serena apologizes for her negligence, though Niall is not thrilled as he thrusts the poker closer to her neck. Barnaby tries one last time to get Niall to come to his senses as despite the unfair death of his daughter, he will never forget the pain if he kills his parents and that no one is to blame for what happened. Accepting defeat, Deeley cries that all he ever wanted was to be a good dad and that he dearly misses her; kneeling to the ground as Serena comforts him while Nelson retrieves the fire poker after dropping it.
As soon as the rest of the DCI units arrive, Niall Deeley is arrested by police; moments after his wife was taken away for aiding Jessica in kidnapping Amy. On one last note, the gun that Niall used in Harry's murder and his failed assassin plot on Butch was said to have been used in several crimes committed in West London. Whether Niall lived in West London and got involved in several crimes or bought a gun used by another criminal for a firearms dealer is unknown.