The series begins with Karl, a trainee clinical psychologist who was a passenger on the first carriage of the Picadilly Line London Underground train - one of the four targets of the 7/7 bombings. After the bomb exploded, Karl was comforted by a woman who held his hand in the smoke-filled carriage as he feared for his life. Cameras also follow Emina, an NHS researcher living in Nottingham. She and her younger sister Edina, who was diagnosed with Down Syndrome as a baby, were born in Sarajevo. Edina is searching for the doctor who helped her family evacuate to safety, and gave Edina the chance of a better life.
