Insidious Intent by Val Mc Dermid

This is a new Tony Hill/Carol Jordan mystery following Splinter the Silence.  Carol has been appointed the head of ReMIT (Regional Murder Investigation Team), a new division dedicated to cracking the toughest cases.  Carol has handpicked her team, which leaves detectives from other squads angry as it insinuates they are not worthy and hinders their advancement.  They engage in mudslinging and the team is again being hounded by the press, who are interested in finding out the details behind Carol's release from her DUI charge.
They are handed a case of a woman found fatally burned in a car parked in a lay-by.  At first thought to be an accident, the forensics team finds the cause of death is strangulation. The efforts of the fire department to put out the flames, removes any fingerprints or other forensics.  It isn't until the second murder that they begin to piece together the movements of both victims and realize that the single unescorted women are being picked up at weddings by a man who has crashed it.
The team finds themselves pushed to find this monster before he strikes again.  Tony Hill is busy with trying to piece together the motive behind the crime, as neither victim knew her assailant before being "dated" after the pickup.  Paula and her partner are dealing with internet blackmail involving their foster son.  Carol is dealing with enormous guilt over the dropped DUI charge, and feels responsible for the deaths of her brother and his wife. Tony has convinced her to completely abstain from alcohol, which she uses to deal with stress, which this case provides a lot of.  The tension ramps up as they race to uncover the perpetrator before he kills again.  Carol has a complete breakdown and Tony tries to save her, which leads to an unexpected and surprising ending.