The gist of the story is that Colin (Romain Duris - The Beat That My Heart Skipped) finally meets the girl of his dreams Chloë (Audrey Tautou - Amelie) only for her to be stricken with a life-threatening illness where a water lily grows in her lungs. The only cure is to surround her in flowers and Colin finds that his life begins to spiral as he attempts to juggle both his home and work life to make ends meet.
The film is based on the cult classic book Froth of the Daydream by Boris Vian, which is actually how the French title translates. The English title appears to refer to the jazz composition by Duke Ellington, for which I assume will have a purpose or meaning in the film.
The film opens in France at the end of April this year so it may not hit UK shores until mid-summer.