In Harrow, north west London, an elderly couple are burgled and attacked by three men in their own home. The men are members of a criminal gang that has been active in the capital for over 18 months, targeting vulnerable and elderly people for their jewels and cash. The gang are experts at leaving no trace behind them: they wear gloves to prevent leaving fingerprints, masks to hide their identities and use bleach to clean up the crime scene. Although detectives believe they know who the men are, they don't have enough evidence to be able to charge them.To try to stop the gang they call in the Flying Squad, an elite team of covert officers, who specialise in armed surveillance and the ambush. The only way to gather enough evidence to secure a conviction is to catch the gang in the act, while committing a burglary. Covert Flying Squad officers begin a surveillance operation they hope will finally bring down the crime network.In Islington, north London, officers from the online child sexual abuse and exploitation unit arrest a man in his 20s suspected of possessing indecent images of children. He denies having deliberately downloaded the images, claiming it was an accident. The team must view and assess thousands of images on his hard drive to gather the evidence to charge him. In south London, they arrest another man also suspected of possessing indecent images. When they arrive at his house, they discover he lives with his partner and baby. They must urgently safeguard the child and establish whether as well as viewing images, he has been creating original content by abusing children himself.