Ground Zero by Aimee Nicole Walker

Ground zero, noun: the center or origin of rapid, intense, or violent activity or change.
Heat, humidity, and homicide are things veteran detective Sawyer Key expects to encounter on his first day with the Savannah Police Department, but the hostile reception from his new partner catches him by surprise. Sawyer isn’t a stranger to heartache and recognizes that Royce Locke is a wounded man who’s reeling from a devastating loss. Relentless and patient in all things, Sawyer is determined to make the new partnership work.
Savannah, Georgia is known for her quirky people, oak trees draped in Spanish moss, and antebellum architecture. Beneath the Southern charm and hospitality, festering hatred and violence is soaring with the summer temperatures. Locke and Key find themselves at the epicenter when their first case involves the death of a former shock jock who appears to be the victim of vigilante justice.
Opposites in nearly every way, the two detectives set aside their differences to take back their city and restore law and order. From this reluctant truce, an intense attraction grows that will either tighten or shatter their tenuous bond. Falling for his partner spells inevitable disaster, but Sawyer’s always been a sucker for wounded things. Sawyer could be the key to the life Royce has always wanted, if he’s brave enough to trust him. The fuse is lit, the clock is running, and the zero hour is upon them. Tick tock.