'Blue Lights' tells the story of three police officers in training in Northern Ireland. They are assigned to Blackthorn Station in Belfast, a city where being a community police officer comes with a lot of pressure and a unique set of dangers. One of the new agents, Grace Ellis, is a mother in her 40s. She gave up her job as a social worker to join the police force, but after only a few weeks she wonders if she made the right decision. The other newcomers, Annie Conlon and Tommy Foster, also struggle with the immense pressure of the track.