1. Episode 1

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.

2. Episode 2

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.

3. Episode 3

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?

4. Episode 4

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?