The Fallen by T. Jefferson Parker

At the dramatic start of Parker's excellent 13th novel (after 2004's California Girl), San Diego homicide detective Robbie Brownlaw suffers a head trauma that causes his senses to get mixed up. The sounds of conversations, for example, are accompanied by colored shapes that reflect the speakers' emotions. But the confusion turns into an asset, as it helps Brownlaw recognize when suspects and witnesses are lying to him—and he encounters lots of falsehoods when he begins investigating the case of Garrett Asplundh, shot dead while waiting for a meeting with his estranged wife. As an investigator for the San Diego Ethics Authority Enforcement Unit, Asplundh had uncovered a widespread corruption scandal—and unleashed plenty of enemies, including city officials, a financier and a purveyor of high-priced call girls.