Levelling-up leaders and environmental activists clash in a small town trying to look to the future. With a sabotaged train and a dead mayor, the activists become suspects.

Jack comes to the aid of an old friend and is sucked into a difficult case where he's pitted against his former mentor. As Nikki and the team start to build a picture of what happened, they learn nothing is as it seems. Dealing with a family of serving police officers, they have to tread carefully as their relationships prove to be another obstacle to overcome.