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.