Follows rookie police officers working in Belfast, a city in which being a frontline response cop comes with unique pressures and dangers.
PSNI probationer Grace promises to help Angela, whose son has fallen in with a notorious gang. But with undercover agents watching, will she be able to keep her word?
The team scramble to deal with a bad batch of drugs while the McIntyres try to cover their tracks. Annie receives terrifying news that has her wondering who she can trust.
A paramilitary-style assault case has Grace determined to bring the McIntyres to their knees. When Gordy pulls away from Angela, she becomes desperate for help.
The police ombudsman investigates the team after a disastrous night shift. Helen uncovers a scandal, while a crisis at home has Grace doubting her career choice.
Mo's side deal goes ahead, risking his relationship with his father. Tommy's firearms exam is brought forward, and Stevie tries to convince Grace to come back to work.
The team work together after the shooting. Stevie clashes with the spooks, Mo learns the truth about his father, and Grace accepts that she might break her promise to Angela.
A year into the job, the team are faced with a drug-fuelled crime wave that leads them into a loyalist estate. A violent clash puts Stevie and Grace's working relationship at risk.
A loyalist gangland feud turns up the pressure on the section. Annie makes an impetuous decision on a night out.
As tensions grow in Mount Eden, a response call forces Stevie to confront his past. Annie deals with the consequences of an impulsive decision.
Lee is the new boss in Mount Eden. Under pressure from Canning to get results, Shane leads Tommy into danger.
Annie's job is on the line. As Lee consolidates power, Stevie and Grace are thrown back together on a response call, with terrible consequences.
Mount Eden descends into chaos as Grace tries to get Henry out from under Lee's control. Happy finally learns the truth.
The arrest of young drug dealer Sandy McKnight begins to expose a criminal conspiracy involving every level of Belfast's society, from wealthy businesswoman Dana Morgan to vulnerable teenager Lindsay Singleton.
A car crash has traumatic consequences for Aisling, while the fallout creates a deadly situation for the section. Grace turns to child protection to try and help Lindsay.
Grace and Shane push boundaries for Lindsay's sake as a threat closes in. Aisling and Tommy respond to a call-out where things are not as they seem, with unexpected consequences.
Grace offers up a secret about her own past in an attempt to connect to Lindsay. Aisling's erratic behaviour forces Tommy to make a heartbreaking decision.
Grace and Sean bring in George for questioning, leading Morgan to take drastic measures to silence him. Shane faces an unexpected situation on a routine call-out.
Grace and Sean are under serious threat, while Lindsay's testimony exposes the Ginleys. Colly takes a risk to go after Morgan, and Fogerty decides Tina is no longer useful.
