Driven to desperate measures, nurse Cath Hardacre assumes the identity of her best friend, an A&E doctor, and finds work in a struggling emergency department.

Cath finds herself falling for Andy and wonders how can she keep hold of the perfect man when she is living a lie. An encounter with someone from her past threatens to expose her secret.

Following his discovery, Andy has a decision to make. A fatal error at work backs Ally into a corner - does she protect her identity or fall further into the lie?

Ally's personal and professional life begins to fall apart. Karl heads up to Edinburgh, desperate to take Molly back to Sheffield. Will Ally stop him before it is too late?