Siegfried Wagner’s operas have fared well at the hands of CPO and now comes Sonnenflammen, eighth of the 18 he wrote. Composed in 1912, it had its first production in 1918, and others followed (including one with Tauber) before it disappeared into an oblivion partly engineered by the ever-contentious Wagner family. The programme booklet mentions recent revivals in the course of a tortuous discussion whose clarity is not helped by an erratic translation. Set in Constantinople at the time of the Fourth Crusade, the plot is of a complexity that could for once accurately be described as Byzantine. It is too involved to summarise but concerns the lives and loves of the Empress Irene, who loves the Emperor Alexios, who loves Iris, who belatedly admits her love for the reluctant Crusader knight Fridolin as he kills himself. The opera ends with the city going up in flames. Siegfried’s libretto provides himself with what he needs, a rapid succession of dramatic moments rather than a larger dramatic structure. The music settles a few obvious debts to his father but has its own energy and lyricism, and a good ear for orchestral colour. Roger Epple gives an enthusiastic lead to his Halle forces and to his cast, including vigorous portrayals of Iris by Eva Bátori and of the tormented Fridolin by Richard Brunner.