Disobeying station rules, John pops into the Cambridge Police Authority, hoping to find intel for Lucy's upcoming assignment. But keeping a low profile proves difficult for our puzzle genius when he finds himself unable to resist consulting on the murder of an influencer. Navigating his way through Cambridge's labyrinth, Ludwig must map out how the killer was able to dodge being seen on camera in an area saturated with CCTV.Meanwhile, Lucy and Henry attempt to connect the dots in their investigation and reach a breakthrough revelation on their prime suspect. But as the pieces fall into place, they can't help but wonder whether their opponent is already one step ahead of them.