A teenage boy lies on the pavement, bleeding from a stab wound; a distraught mum watches, in mute shock, as her daughter suffers a terrifying fatal asthma attack; a young girl is gang-raped and her stricken boyfriend takes an overdose; a disturbed young man flings himself in front of a speeding train at the stroke of midnight on New Year's Eve.

Few people can imagine living in a world where such situations are part of everyday life. Yet for veteran paramedic Lysa Walder, these and thousands of other emergency call outs are part of a day's work: scenes of tragedy, heroism loss and horror - but also stories of triumph and humour.

Lysa has been a paramedic for over twenty years, working for the London Ambulance service - the world's biggest and busiest free service - for much of that time. Here, she reveals what it's really like to work in a job that brings paramedic teams face-to-face with death - and destiny - every day.