Emma Barton is feeling understandably on edge after killing estranged husband James.
She's already had the police round asking awkward questions.
The scheming mum is banking on Ashley Thomas being the only potential witness - after all, with his worsening dementia, what could he actually remember?
And, even if he could, who would ever consider him a credible witness?
Well, she may be a medical professional, but she is not an expert on everything - and gets the shock of her life when she realises that Ashley is beginning to remember events from the fateful day.
The drama unfolds as Ashley traces his steps back to the scene of the accident. By coincidence, guilt-ridden Emma has also returned there.
When the vicar spots her on the footbridge, some kind of memory is obviously triggered.
Emma is clearly troubled, as she later visit Ashley and cruelly tries to muddle his mind; she says he can't be sure of what he saw, and when he protests that he does, she starts going round in circles to confuse him even more.
Not too surprisingly, Ashley grows distressed - and she even comforts him!
Emma may be feeling relieved that she has managed to put the poorly vicar off her scent... but she hasn't noticed Ashley's video camera has caught it all...