Gun Machine

This morning Detective John Tallow was bored with his job.
Then there was this naked guy with a shotgun, and his partner getting killed, and now Tallow has a real problem: an apartment full of guns. Old guns. Modified guns. Arranged in rows and spirals on the floor and walls. Hundreds of them.
Each weapon is tied to a single unsolved murder. Which means Tallow has uncovered two decades' worth of homicides that no one knew to connect and a killer unlike anything that came before.
Tallow's bosses don't want him to solve the case. The murderer just wants him to die. But there's a pattern hiding behind the deaths, and if Tallow can figure it out he might even make it out alive.