X-Men: First Class #14

Direct Edition

The X-Men and their new member, Machine Man, battle the Lava Men. During the fracas, Dr. Stack gets a message that the other Machine Man robots have gone crazy back at the lab. Xavier tips off his X-Men to the problem but they are unable to keep Aaron from diving into the Lava Men in their natural element and melting away. They save the brain and Dr. Stack begins using it to construct Machine Man number X-51.