When registrar Sally Fortune (Manjinder Virk) collapses, Monroe (James Nesbitt) is faced with the terrifying prospect of operating on a colleague. Fortune's condition is serious - she has an aneurysm in her brain which could burst at any moment, and one wrong move during surgery risks leaving her permanently damaged. Fortune places her trust in her mentor, but when the procedure begins to go badly, Monroe has to hold his nerve in a race against time to save his registrar.