Moped rider Martin is fighting for his life after a collision with a lorry in London. Doctors are concerned he may have severe head and spinal injuries after the wheel of the lorry pressed against his neck. Also in London, police officer David is diagnosed with a heart attack after suffering a sudden cardiac arrest at the gym. He is taken to Barts Heart Attack Centre for an angiogram and an emergency heart bypass operation, which successfully treats a blockage in his coronary artery. In Northumberland, cyclist Julian comes off his bike with a nasty facial injury. Once in hospital, he begins to deteriorate and suffers a major stroke before undergoing an emergency operation to remove part of his skull and relieve the swelling in his brain. Julian faces a long process of rehabilitation after his injuries.