Spider-Man explains that, a few days ago, he rescued a guy from being hit by a bus, who then showed his gratitude to the web head by stabbing him in the stomach. Before Spidey could catch him, the man had vanished. Since then, random people have kept attacking him and disappearing. Spider-Man was eventually able to catch a glimpse of Chameleon, who he correctly deduced was behind all the attacks. Unfortunately, Chameleon's hit-and run strategy has kept his Spider Sense buzzing constantly, leaving Peter afraid of what to do next. He can't return to his apartment in case the Chameleon tracks him there, nor can he take the chance of attacking the first suspicious party he sees in case he gets it wrong (as he just did with Deadpool).
Acknowledging that, while he has fooled him into thinking he's Spider-Man, Chameleon has picked up on the voice difference, meaning he'll have to commit one hundred percent to being the web slinger lest Cammy finds the real deal, Deadpool tries out webslinging before coming across a mugging in progress. Confronting the purse snatcher, Wade questions why he's practising the tool of his trade in New York, the super hero capital of the world, knocking the man out before he can finish his answer. Deadpool then webs the guy to a passing police car so he won't have to string him up. Wade also grabs a nearby bystander to test if it's really Chameleon, but typically it's an innocent guy, who Pool releases. He then notices several snakes passing by his feet, all of them headed to the same building, leading Wade to conclude that he's dealing with an animal-themed villain. "Classic Spider-Man".
Entering the building, Deadpool finds the staff are being held captive by 'the Masssster' (sounds like an axed member of the Snakemen from Masters of the Universe), who has a very specific scheme in mind. You see, the facility is known for it's work in synthesized tissue, and the staff do a lot of that work through cloning mice. Basically if the mix of matter is right, they can transform anything into an instant mouse. With this in mind, the Masssster plans to use the facility to create an endless food supply for his army of snakes!
...Yeah, as Deadpool points out, it's pretty dumb, and as Spider-Man is a "champion against dumb" (in Deadpool's words anyway), he leaps into battle, almost immediately knocking the villain into some of the facility's equipment, causing a lot of blue energy to crackle around him. One of the scientists informs "Spider-Man" that the matter-converting energy is loose and, since the Masssster has a psychokinetic connection with his snakes, it will read them as one single batch of matter to be converted into mouse. Wade assumes that this means they will all become regular, tiny mice, but the scientists corrects him, "not mice...mouse". Now transformed into what looks like a cross between a white mouse and a T-Rex, the Masssster breaks out of the building and starts rampaging through New York. The scientist tells Wade that because the creature is so massive, the energy used to build it must be unstable and thin. He reasons that, if "Spider-Man" can injure the less connected internal tissue, then the monstrosity lumbering before them should simply fall apart.
Satisfied, Deadpool only shoots the fake Spidey in the knee cap, while the real one suggests that the Chameleon tell him how he pulled all this off, lest he have Deadpool for a roommate. Chameleon reveals that he was able to track the web slinger via his new batch of web fluid that Doctor Octopus developed when he possessed Peter's body as the Superior Spider-Man (it's a lot nicer to talk about that in the past tense) - whose capture of the Sinister Six and constant bragging fuelling Cammy's desire for revenge - explaining that the new formula leaves trace radiation that's "exceedingly simple" to pinpoint. Deadpool comments that Spidey should probably fix that, to which the web-head responds that he'll get right on it. They then knock out the Chameleon with a double punch to the face, both of them rightly labelling him as a creep.
Shortly afterwards, our two costumed adventurers - both now wearing the right costumes - enjoy a much-needed hot-dog break under the starry-lit sky. Conveniently for us, Wade has just finished telling Peter everything that transpired while he was unconscious. Spider-Man thanks Deadpool for the assist, but adds that he has a feeling he's going to be spending the next month repairing the damage Wade did in his suit, snagging a copy of the Daily Bugle to check "his" exploits. Much to his surprise, and subsequent annoyance however, the headline for Page 1 reads "HOPE FOR Spider-Man", though Deadpool seems more interested in the closing of the Cats musical...
Jacopo Camagni handles the artwork for this annual and for the most part, it's pretty awesome. The facial designs for the characters are rather cartoony, but there's a consistency to them that prevents the work from looking sloppy or disproportionate. The vibrant colours by Matt Milla also add to the 'nuts factor'. The only thing that didn't really work for me was how expressive the eyepieces in Spider-Man's mask were. Usually I have no problem with this, but in this case, it takes away from the otherwise solid contrast of Wade and Peter in the Spidey suit - Camagni even includes the little flappy bit that Wade has at the back of his Deadpool mask when he wears Spidey's, which is some clever attention to detail - since there's barely a consistent look to the lenses when Peter wears the mask, and some of the expressions done with them are a little weird, though on the flipside there are several that look pretty cool. One shot in particular reminded me of the style employed by Marco Checchetto, one of my favourite modern Spider-Man artists. There's also a bit of inconsistency with Deadpool's face. When we first see him unmasked, he looks pretty much in line with the current depiction of his scarred visage, whereas the second time, he instead resembles a cartoon zombie.
Nitpicks aside however, this is an awesome and hilarious 'sort-of' team-up between Marvel's two biggest blabbermouths. If you like either of these characters, you should definitely check this out...