In the past year, over 2000 officers have joined the ranks of the Metropolitan Police, tasked with keeping the streets of London safe for its eight million residents, 24 hours a day. Over 50 per cent of new Met officers are from outside London, and Yorkshireman Tom Hebblethwaite has his work cut out finding his way around the city streets. During his on-the-ground training he must achieve some vital goals, from making an arrest to learning to march before he can graduate and 'pass out' in front of top cop and fellow northerner, Commissioner Sir Bernard Hogan-Howe.The streets of London are a challenge for even the most experienced police constables, and response officers Caroline Hay and Karl Davies are old hands at dealing with the ups and downs of policing the public in Camden, north London. While putting up with verbal abuse from angry buskers is just part of the job, it's protecting some of society's more vulnerable individuals that makes Caroline reflect on why she joined the service.In east London, Detective Jason Weald is nearing retirement and must call on his years of experience to get to the bottom of the tragic death of a four-month-old baby. His team struggle to keep their personal and professional opinions separate as the quest to find justice in this emotional case divides the homicide detectives.