Mrs Shim Is a Killer by Jiyoung Kang

In this savage and side-splitting literary thriller, an ordinary woman dives headfirst into a world of petty criminals, crooked cops, and accidental assassins. Around her orbit a washed-up fixer blackmailed by his boss's daughter, a policeman's wife undercover at a third-rate detective agency, a ghost marriage-broker with an attraction to hairdressers, and a son who unknowingly becomes her rival. What starts as survival turns into vengeance. For Mrs Shim is done with being everyone's doormat.