Some background, courtesy of Kerry Wilkinson:
Back during the Secret Wars, Spider-Man got himself what he thought was a new costume. It turned out to be an alien symbiote that wanted to possess his body. Spidey rejected it, however and it was left holed up in a church tower.
Shortly afterwards, Eddie Brock, a journalist with the Daily Globe lost his job after his Sin-Eater identity story was proved to be fake by Spider-Man. Wanting to end it all, he first went via a church to say his last goodbyes. His hatred of Spider-Man was picked up by the symbiote however and the two bonded to form Venom - a crazed killer who wanted nothing more than to kill Spider-Man.
In their many battles, Spider-Man triumphed consistently - even though his Spider-Sense doesn't pick up on Venom's presence. One time when Brock was in prison, however, the symbiote gave birth to another version of itself. This new symbiote bonded with Cletus Kasady - Brock's psychotic cellmate - and together the two became another crazed killer, Carnage.
When Carnage first escaped, Spidey teamed up with Venom and the Fantastic Four to save the city and re-incarcerate Kasady. Since then, Venom has re-escaped too and, after Spidey helped save Brock's ex-wife, formed an understanding with Spider-Man that he won't cause anymore trouble and that the two of them will stay out of each other's way. Most recently of all, in one of the best Spider-Man books of all - Spectacular 200 - JM DeMatteis scripted the death of Harry Osborn. He had gone crazy as the Green Goblin, wanting to blow up most of the city's leaders. After MJ and little Norman entered the building he was fighting Spider-Man in, however, he came to his senses, even saving Peter from the explosion, before he died in front of them.
Eddie Brock arrives at LaGuardia Airport and quickly becomes Venom and starts to track Carnage. At the Holy Ghost Church, Cloak leaves Spider-Man to hunt down Shriek, who killed his partner Dagger in "Web of Spider-Man #101". Spider-Man leaves to hunt down Carnage, as well, reflecting on something Cloak said about losing family and friends. The villains in question are regrouping on a rooftop, and after Carnage claims that Spider-Man is his kill, the hero arrives at his apartment and receives an earful from Mary Jane. After the two lover's spats are settled (Carnage's ends better than Spider-Man's), both the heroes and villains return to their missions in life.
While Carnage is slaughtering people in the park, Spider-Man is wondering where the crimson-clad killer could be. After several minutes, he finds not Carnage, but the Demogoblin. The Demogoblin throws a pumpkin bomb of despair at Spider-Man, causing the web-slinger to just give up. Several blocks away, Venom learns where his quarry is at, and heads to the park. Spider-Man, meanwhile, breaks out of his despair thanks to a priest. After the Demogoblin escapes, Spider-Man decides to head home in order to recooperate.
Venom, meanwhile, has found his quarry, but is quickly dispatched by Carnage's cronies. At the Parker residence, the less-than-happy couple are watching the news when there's a knock at the door. When Mary Jane goes to answer it, Venom himself tumbles into their aparment, beaten.
Oddly enough, this issue started on parallels between Spider-Man and Carnage. Each was returning to their significant other, and both had to convince them that what their words rang true. Interestingly, Carnage had more success than Spider-Man. This issue only served to introduce Venom fully into the plot, as well as Demogoblin.
The art has been the best yet of the arc, with the exception of Carnage who fluctuates in stature. Sometimes he looks thin, other times burly.
The fact that I could summarize the events of the book in three paragraphs speaks poorly of the content of the book. So, while all the characters act and speak as they should, the book loses a half-a-web for lack of content. On the visual side of things, the book is quite strong with only a minor qualm, so no lost webs there.