Carmen is among the most popular operas for all the obvious reasons: great characters, a gripping story and fabulous music. But what sets it on a pinnacle is an amazing combination of three factors: a sizzling gipsy heroine (one of the most psychologically complex and compelling characters in all theatre), great atmosphere (Spain, hot sun, the bull-ring) and the prodigality of melodic invention - one great tune after another, at least a dozen of which are the staples of Madison Avenue and the animated cartoon. Like a surprising number of opera-house staples, Carmen was not a success at its first performance. In fact, it is likely that its failure contributed to the early death of the composer. But as Thomson Smillie shows in his accessible introduction, the emotionally driven nature of its heroine and her admirers, Don José and Escamillo, makes Carmen unforgettable. As always in the Opera Explained series, the music itself plays an integral role.