One of the joys of Joss Whedon's writing in Astonishing X-Men is the relationship he portrays between Emma Frost and Kitty Pryde, two strong female characters.

Snarky and insecure, Emma just can't help clashing with goody-two-shoes Kitty. But Ms Pryde is no pushover, and unlike the rest of the X-Men, she hasn't forgotten that Emma used to be a villain.

So perhaps it's no surprise that when Emma snaps and apparently turns on the rest of the team, it's Kitty who leads the fightback.

But there's more to the story than this, and at the heart of the tale is a mystery - what's really going on with Emma Frost?

Of all Joss Whedon's X-Men tales this is the most complex, as the X-Men experience a series of dreams and illusions, and it's unclear what's real and what's not. It demands more from the reader than the average comic book, but it's worth it.