999: What's Your Emergency? follows members of emergency services throughout Britain as they work together to tackle crime and disorder, providing insight through the eyes of the police, fire, and ambulance services using a mixture of fly-on-the-wall footage taken at incidents and retrospective interviews with the people and staff featured.

With rig technology inside the emergency vehicles to call centres to multiple crews on the ground 24/7, the series captures in a unique way the issues that face Britain today, from the emergence of new drugs and the despair of domestic violence to the way we parent our children and those who slip through society's safety net.