Fox describes X-Men: First Class as the beginning of the X-Men saga, following Charles Xavier and Erik Lensherr before they became Professor X and Magneto, respectively. The story sees Xavier and Lensherr working together with other mutants to fight off a great threat. During this battle, the two mutants grow apart, ultimately resulting in the war between Magneto's Brotherhood and Professor X's X-Men.
X-Men: First Class is the fifth entry in the X-Men series and second prequel, following last summer's X-Men Origins: Wolverine, which opened to $85.1 million and ultimately closed with just under $180 million. The X-Men series began in 2000 with X-Men, which grossed $157.3 million. X2: X-Men United made $214.9 million three years later, with 2006's X-Men: The Last Stand completing the initial trilogy with $234.4 million (the highest grossing entry in the series). Worldwide, the series has made over $1.5 billion.
Vaughn's Kick-Ass opened to $19.8 million last month and has made $42.7 million in 18 days. Vaughn, who previously directed Layer Cake and Stardust, is no stranger to the X-Men, as he was originally signed on to direct X-Men: The Last Stand back in 2005 before leaving the project due to creative differences.