X-Men / Spider-Man [X-Men and Spider-Man] #2

As Spider-Man digs through the files of the recently deceased Kraven, he finds information on an old adventure he had with the original X-Men where the villain took genetic samples of the mutants for Mr. Sinister. Spidey takes this information to the current team only to find that they are in the middle of dealing with a mutant massacre. When the X-Men hear Sinister's name, they ask Spider-Man to help them track him down and they head into the Morlock tunnels. After a battle with Sinister's agents, the Marauders, our heroes find an old lab with twisted, dead clones of the X-Men.