Why then did someone brutally murder Victor Whyte, an elderly man chiefly known for his dedication to helping the gay community?

Inspector Claire Summerskill and Sergeant Dave Lyon investigate and are drawn into the world of the Hereford and Worcester Lesbian and Gay Switchboard, a telephone helpline for LGBQT+ people. Operatives and callers help piece together a picture of the murdered man, and gradually a surprising picture of Victor emerges with the possibility of a murderer in the very last place Summerskill and Lyon would have thought of.

Even as they deal with this latest case, the two officers are forced to deal with turning points in their personal lives. Can Claire balance the demands of her position as an inspector with those of her husband and children? Is Dave ready to settle into a relationship with earnest young police officer Joe Jones or will he opt instead for the excitement of an almost certainly shorter fling with charismatic MP Sean Cullen? And what exactly is Sean's real motivation?

Crossing Lines is the fourth in the series of Summerskill and Lyon police procedural novels.