Straight Back by David Menon

Jeff Barton returns from his holiday to see his late wife's relatives in China in a relaxed and refreshed mood but that's soon put to the test. He's used to being under pressure to find answers but this is different. He begins to feel there's a force within the force that doesn't want him and his team to make any progress. But he's a police officer. He solves crimes. He doesn't let anyone deter him from his task no matter who they are and the more he pulls at the thread of information that comes his way the more he believes that the murders are a warning. But from who and for what? Why did sixteen year old Sheridan Taylor go off that night? What does it have to do with her school teacher and why can't Jeff have any extra resources for his investigation?