Within the bright colours of this exhilarating survey of the Blue Rider group of avant garde artists, who worked in Munich and the Bavarian Alps in the years before the first world war, horror lurks. Look at Wassily Kandinsky’s paintings of the medieval Bavarian town Murnau, and you might wonder if there’s any connection with the film director FW Murnau who made the silent vampire film Nosferatu? Yes – he took the town’s name after befriending the Blue Rider artists there. So welcome to the land of spectres. Marianne von Werefkin’s eyes, for instance, blaze red from her self-portrait. Green,...