A funeral in blue - Anne Perry

When her brother arrives on her doorstep, Hester Monk is shocked - as much by the unexpectedness of the visit as by the reason for it. For since her marriage to Monk, Charles and his elegant wife, Imogen, have kept their distance.
But now Charles needs Hester's help. He believes Imogen is having an affair - there can be no other explanation for her recent strange behaviour. However, before Hester is able to investigate, a tragedy occurs. In a nearby artist's studio two women have been brutally killed. Having left the police force with extreme ill feeling between himself and his superior, the last thing Monk wants to do is face the demons of his past. But, in the course of his work, Monk is left with no choice but to visit his old adversary, Runcorn, and involve himself with the sensational murder case.