Strike and Robin perform surveillance on Mad Dad at the request of his soon-to-be ex-wife. Mad Dad is a wealthy international banker with his own company whose family lives in Edge Street in Kensington. Because his and his wife’s divorce proceedings have become contentious, he has a habit of stalking his young sons and verbally accosting them in public. He often does it at their home and school, and even the Natural History Museum when his younger son visits it.

It is Strike and Robin’s job to photograph these incidents so that they’re documented as evidence of violations of the custody agreement.