The Iago Factor

DI John Hunter is back again. Faced with one of his 'Thursday' murders - a young girl dressed in police uniform fished out of the Thames - he knows he is on a hiding to nothing, but that one goes on the back burner while he investigates the murder of a senior police officer, Commander Freddie Sloane, who headed up Vice.
Someone out there is determined to destroy John's marriage, using false evidence of his and Jane's apparent infidelities, and Jane's involvement in Freddie Sloane's murder. Her pistol, kept in their personal safe, was used to kill the Commander, and other equally damning evidence piles up against her, leading to her arrest on what appears to be a slam-dunk case.
John is taken off the case but continues investigating, receiving death threats from the Russian mafia along the way.
One of his suspects is Freddie's eldest daughter, and she is involved with a woman who runs a home for battered women. John is surprised to find one of his old loves, Maria, a technical wizard, in charge, and while there also sees a young Russian girl, who is hiding from the mafia.
He arranges to have a colleague inserted undercover into the home, sure the answer lies in that place.
His friend Paddy has been eavesdropping on the Russians and tells John they are about to raid the home.
He and Paddy race there but arrive too late: the girl has been taken and Marie killed.
John adds two and two and finds the killer, but for personal reasons wants to 'look the other way', as he did in the 'Infinity' affair..
His crime partner will not agree and he is unable to do so, which results in the murderer's suicide, but John has been told enough for him to realize that both murders were related, and for Jane to be released from custody.
With the case closed, he attends Freddie's funeral, only to find out that he has been played throughout like a worn out old one-stringed fiddle.