Ystad is unusually well-served by literature for a town of its size, almost entirely thanks to Henning Mankell.
Faceless Killers (1991) is the first Kurt Wallander novel and the place to start if you want to follow the detective who has come to define Ystad in international imagination. The murder of an elderly farming couple sets off an investigation that pulls in the politics of refugee policy in early-90s Sweden.
The Fifth Woman (1996) is one of the strongest in the series, with Wallander chasing a methodical killer through the Skåne countryside that surrounds Ystad.
The Pyramid (1999) collects five stories from earlier in Wallander's career, useful for new readers who want backstory.
Italian Shoes by Henning Mankell (2006) is set further north on an island in the Stockholm archipelago, but it shares Mankell's clear-eyed view of older Swedish men and is the right companion to the Wallander novels.
The Long Ships by Frans G. Bengtsson (1941, English 1955) is the great Viking-age novel of southern Sweden, set partly in Skåne not far from Ystad. Funny, brutal, and a useful reminder that this coast has not always been quiet.