“I hate Venice,” says Luc Tuymans. “Decay, morbidity, memory: it is the most likeable city where you can be uncomfortable — in a comfortable way.” The grumpy Belgian painter has just finished installing a stunning and unexpected retrospective that opens this weekend at Palazzo Grassi. Any artist would be thrilled to exhibit across this neoclassical courtyard interior and movie-star staircase, and from the first glance at two watery showpieces looking on to the glittery, serene Grand Canal, it is clear how Tuymans — magnificently and menacingly — both exploits and undermines the setting. “Murky Water” (2015) is a dystopian triptych of acrid yellow-green reflections of street lamp and car in the algae-ridden, litter-strewn surfaces of a putrefying Dutch canal, a composition enlarged from a blurry Polaroid shot. The velvety indigo-violet-black seascape “The Shore” (2014) is more sinister: it features a distant line of blank figures, hands raised in surrender, delineated by wipeout — Tuymans smudged the dark ground and painted the gaps in white blots. They represent submarine crew members about to be shot — the source is a still from Don Chaffey’s 1968 adventure movie A Twist of Sand — but the tiny exposed huddle could be any vulnerable people. The painting is Goya-esque in its blackness and expression of terror. Tuymans’ unease about Venice mirrors exactly the discomfort created by his paintings. Their themes of disintegration, death and the challenge of collective memory are deeply disturbing — the more so because Tuymans aestheticises trauma with supreme painterly seduction. “Wandeling” (1989), an idyllic snowscape with pine trees and figures like little crosses, is Tuymans’ imagining of Hitler and his entourage strolling outside Berchtesgaden, planning the “final solution”. In “Frozen” (2003), a bright halo glimmering around a gloved hand on what could be a treasure chest signals nuclear breakdown; the hand belongs to a worker cooling a Chernobyl reactor element. “Strangely enough, people could come out of this show and say it’s beautiful,” Tuymans snarls. “I think that would be funny.”