Dom Littlewood goes behind the scenes at some of Britain's most secure institutions to see how they keep us and the country safe. Today, Dom visits Britain's busiest airport, Heathrow, to see how passport control operates. He sees how police horses are trained, then joins mounted police in south Wales as they patrol Cardiff's streets to keep over 60,000 music fans safe at an Ed Sheeran gig. And home security expert Sukie Madahar gives advice on how to protect cars from catalytic converter thieves.

Dom Littlewood takes to the trains to find out how rail enforcement officers deal with suspicious packages at one of London's busiest stations. Then he goes home to Southend-on-Sea to see how the police are working with the local community to secure the streets. Home security expert Jenny Donaldson helps a delivery driver in Bristol who had his specially adapted motorbike stolen from outside his house.