Mit : David Mitchell, Anna Maxwell Martin,

A body falls from the fourth storey of a construction site. Was it just a terrible accident or a perfectly executed murder? John's team think he's losing his touch when he latches on to a far-fetched theory and starts pointing fingers. When things don't quite add up, John begins to question his abilities both at work and at home, whilst Lucy's frustration at their lack of progress in finding her husband reaches fever pitch.