When Fantastic Four twelve by Stan Lee, Jack Kirby and regular inker Dick Ayers, hit the stands Marvel was getting its roots laid down. With the success of the Fab 4 they had launched the Hulk in his own book and in titles like Journey of Mystery, Tales to Astonish, and Tales of Suspense they had seen the debuts of Thor, Ant-Man, and Iron Man respectively. Strange Tales had seen a Human Torch series which established a smidge of continuity into the comics and even a surprise hit called Spider-Man was finding purchase on the stands. It's in this environment that the Hulk guest-stars in the FF, a clear effort it looks to me to broaden his exposure and strengthen sales of his own book which was swiftly faltering.
The story begins in typical FF fashion with the Thing being mistaken for the Hulk and taking umbrage at the confusion. He and the team are at that very moment being asked by General Thunderbolt Ross to check into the threat of the Hulk in regards to a special government project which will protect cities from missile attack. Someone (presumably the Hulk) is sabotaging the project. The team jumps into the a brand new Fantasti-Car and rush to the desert test sites and meet Dr. Bruce Banner and his assistant Rick Jones. After some mutual glad-handing the FF interrupt an attempt to sabotage a test by a mysterious creature who seems to attack from beneath the ground.
Some of the details on this one are pretty fun. The Thing and the Hulk battling it out is a natural for Marvel and they do a bit of slugging here, but Lee and Kirby are careful to keep the contest inconclusive, though to my eye the Hulk seemed to be the stronger of the two with the Thing relying on his more developed fighting skills. I love the debut of the Fantasti-Car, one of Kirby's best vehicle designs and a real indication where the machine designs in the series are headed. Another hilarious detail is the the spy is caught because is literally a card-carrying Commie as Rick Jones finds just such a card in his wallet. It's a clumsy detail but does suggest that the Reds were quite able to infiltrate this test facility quite easily.
The next time we see the Hulk he will be in his own magazine one more time before that closes up shop. And the artist on that effort will be a surprise. To be Hulkinued for sure.