When Chris Regan started dating coworker Kelly Cochran, he knew she was married. But he had no idea of the wedding day pact she had made with husband Jason. Chris had become entangled in a love triangle that would see two people lose their lives.

Amin Miah wanted a devout, homely wife to start a family with. Mahmuda Khatun wanted a career, a social life - and her family off her back. Their differences were irreconcilable, and one of them would choose the violent way out.

Lisa and Thomas Infante were childhood sweethearts who grew up on the same street. It seemed inevitable they would end up together. But their marriage was volatile, and when one of them found love elsewhere, the consequences would be fatal.

The women in Malcolm Webster’s life seemed prone to bad luck. One died in a car crash. Another suffered a mysterious illness. A third, a keen sailor, found her life jacket punctured. How long before police realized this was more than coincidence?

Stephen and Anne Searle were the grandparents at the helm of a large, close-knit family. But Stephen was having an affair, and Anne had been pushed to drink by her husband’s controlling behavior. Neither was destined to enjoy a peaceful retirement.

Ann Marie and Anthony Anastasi had four children, a big house on a desirable street… and a younger lover living in their basement. It was a toxic love triangle and one that was destined to end in tragedy.

The Donnelly family’s neighbors knew they were unusual. Christopher and Hannegret were rarely seen outside the house, and the children were home-schooled. But no one could guess the violence taking place within their home. until it was too late.

Ian and Sally Lawrence were a glamorous couple, and they looked like they had it all. But their marriage suffered when Ian’s star started to fall as Sally’s career rocketed. And when the couple suffered a terrible car crash, only one came out alive.

High-profile politician Kathy Augustine married nurse Chaz Higgs after a whirlwind romance. They were an unlikely match, and when their marriage hit the rocks, Chaz decided to use his medical training to commit an undetectable crime.

Denise Williams was devastated when her husband Mike disappeared on a hunting trip. He was feared drowned. But Mike’s mother Cheryl didn’t buy it, and after years of relentless campaigning, she finally uncovered the truth about her son’s death.

Paul Novak was a thrill-seeking paramedic who loved the hustle and bustle of the city. His wife Catherine was a homemaker and volunteer who preferred small-town life. Unable to reconcile their differences, Paul decided to plan the perfect crime.

Raneem Oudeh came to the UK from Syria to escape war, looking forward to a brighter future for herself and her son. Everything was falling into place until she met Janbaz Tarin, a man who saw no boundary between love, obsession, and extreme violence.

Kelly and George Worgan looked like the perfect parents, playing happy families on Facebook with pictures of days out. But behind closed doors, they had financial struggles and rows. When their marriage ended in murder, no one saw it coming.

George Young worked his fingers to the bone to give his loved ones a better future: his wife, Tia, their three sons, even his friend Tim Lee. How was this generosity repaid? With deception, infidelity, and a plot to cash in on his death.

Bob Poynter was old enough to be Chacey’s father. And he was married. But those were minor obstacles to her. However, when their romance hit the skids, Chacey enlisted yet another of her lovers to help bring the marriage to a brutal end.

Melanie and David Clark’s marriage was the definition of toxic. He was controlling and angry, and she had affairs. They seemed unable to tear themselves apart - until one violent incident ended their marriage for good.

Arlene McInnes and Nat Fraser had a whirlwind romance, marrying and having their first child within 18 months of meeting. But Nat soon revealed himself as a womanising, violent bully. When she rebelled against him, he hatched a plot to punish her.

Brian and Carla Burns were both medics in their 40s when they met and fell in love. But married bliss didn’t last, and divorce proceedings were messy. Carla disappeared, and fingers pointed at Brian, but he was ready with a bizarre explanation.

Lois and David Riess were grandparents and business owners. Lois was also a gambling addict who would do anything to feed her habit. David became the first victim of a murderous rampage that earned Lois the title of America’s most wanted grandmother.

Tiffany and Keland Hill were military veterans with a shining service history. But while Tiffany still lived to serve, Keland lived to control, stalk and terrorise his wife. He was extremely violent, but no one predicted his final act of brutality.

Aliny and Ricardo Godinho had four children and a relationship history that spanned 17 years. While Aliny put her kids at the centre of everything she did, for Ricardo they were a morbid obsession, and one that would lead to a shocking, brutal crime.

At the age of 16, Sana Muhammad had an arranged marriage to Ramanodge Unmathallegadoo, a man almost twice her age. She managed to escape the unhappy relationship and found new love, but Ramanodge decided she would never get to enjoy her new life.

When Frances Araiza met Bill Hall Jr, he was a 16 year old with big ideas. Fast forward three decades and they were grandparents with a multi-million dollar empire. But behind closed doors, their marriage story was heading for an explosive finale.

After leaving an arranged marriage she claimed was abusive, Faria Khan could have moved on. But she wouldn’t be satisfied until estranged husband Nawajid was dead. And she knew exactly who to ask to help her.

Steven and Crystal McDowell were never a good match, and for years after they split, Steven deluded himself that reconciliation was just around the corner. Then, Crystal disappeared during a deadly hurricane. Was she the victim of a natural disaster?

Glyn Dix met Hazel while he was serving a life term for a brutal rape and murder. After convincing her he had been framed, the couple fell for one another. But five years after his release from prison, Glyn finally showed Hazel his true colours.