This is a tribute to Marvel's greatest artistic and literary achievenment, The Dark Phoenix Saga. The Dark Phoenix Saga by Chris Claremont and John Byrne is widely held as one of the finest storylines in the Marvel Universe. While the trade paperback contains most of it, the story really ran for about 25 issues *before* the issues reprinted in the TPB.
It started as a subplot when the mutant X-Man, Jean Grey, was possessed by the Phoenix entity, a being of great power that slowly transformed her into one of the most powerful superbeings in the universe. The story contained in forementioned tradepaperback is the climactic end to the story. As Phoenix, Grey becomes more and more powerful to the point where she can no longer fully control the urges that her godlike abilities give her. A shadowy organization called the Hellfire Club seeks to control her and manipulate her power to their ends. Meanwhile, her fellow X-Men, including her love Scott Summers (a.k.a., Cyclops), seek to infiltrate the Hellfire Club. Ultimately they end up defending Phoenix after she has unleashed her powers in ways they never dreamed imaginable.
Each of the X-Men has their moment to shine in this story.
Of particular note is the sequence wherein Wolverine singlehandedly rescues the entire team.