In 2013, a young Romanian woman approaches the Police Service of Northern Ireland (PSNI) about a gang that had forced her into prostitution.

Former detective chief inspector Dougie Grant and detective inspector Rachel Miskelly of the Serious Crime Branch are tasked with investigating this challenging case. Their first priority is to identify other victims to gather crucial evidence and help them escape exploitation. But inside the brothels, fear and grooming have silenced vulnerable women, making the task almost impossible.

With determination, Rachel and Dougie turn to digital forensics and piece together the movement of victims across international borders. They recall how, in a groundbreaking human trafficking investigation, the PSNI join forces with Swedish authorities, Europol and Romanian law enforcement to bring the leaders of this organised crime gang to justice.

In Stockholm, Detective Per Hjort and public prosecutor Eva Wintzell share unique insights into evidence gathering through covert surveillance and wiretaps. Through this, they're able to identify another victim and share intelligence to build a stronger case.

The most profound impact of this case is on the thirteen women who were rescued. Diane Hickey and Heather Woods from Women's Aid shed light on their efforts to collaborate closely with police and support victims throughout the investigation and legal process

In 2019 Pat McCormick, a 55-year-old father of four, is reported missing when he fails to come to work one morning.

When detectives speak to Pat's ex-wife and children, they get a picture of a loving and reliable father. So when he also fails to show up one morning to bring daughter Morgan to school, and no trace of him can be found, all are left gravely concerned.

Officers believe they're dealing with a missing persons case. But as they dig deeper, they uncover a call made by Pat to police on the night he disappeared.

It is clear from the call that Pat was concerned about his well-being and feared someone was out to get him. With this shocking information, the case is escalated to a possible kidnapping, and detective Heather Campbell is brought in to run the inquiry.

Heather and her team scan hours of CCTV to trace Pat's movements. They get their first break when footage shows him walking into the flat of his girlfriend, Lesley Ann Dodds, in Comber, County Down. However, he is never seen leaving.

Detectives also discover Lesley Ann is engaged to another man, David Gill, also captured on CCTV in Comber on the night of Pat's disappearance.

As a complicated love triangle emerges, this missing person case is declared a murder investigation, and the search for Pat's body begins. But detectives can find no sign of his remains.

If Detective Campbell is to put Pat's killers behind bars, she and her team must use everything at their disposal, from appeals to the public to cell site analysis and the use of specialist underwater search teams, to find the body. Colin Ferguson, search team leader, gives behind-the-scenes insights into his complex search operation.

Meanwhile, in a heartfelt account, Pat's daughter Morgan recounts the trauma she and her family endured while waiting for answers.