Laura, 29, has an incurable brain tumour. To extend her life, she needs it removed, but there is a catch. In order to make sure that all the tumour is removed, surgeon Ismail Urghratdar must sacrifice tissue from a healthy part of Laura's brain - the hippocampus - which is responsible for storing memory.
Sixty-six-year-old Patsy undergoes a major heart operation as surgeon Jorge Mascaro tackles a massive aneurysm in her aorta, which is so swollen it's in danger of bursting. Andrew has been living with a tumour slowly wrapping itself around a crucial nerve in his face, upon which ENT surgeon Richard Irving will operate.
Cameras focus on Gary, who has a rapidly growing paraganglioma - a rare tumour that has lodged itself in his spine. He knows that leaving it in place will almost certainly lead to paralysis. However, the operation itself carries a huge risk. One wrong move during surgery could damage the nerves irreversibly.