These two issues (Amazing Spider-Man #430 and #431 for the record) are a soft spot for me as they are some of the first Spidey comics I ever read.
At this point, Norman Osborn had taken control of the Bugle via threatening the lives of Jonah's loved ones, and had issued out an award for the public to catch Spider-Man. So as you can probably guess, the public is even less welcoming of him than they usually are and Spidey is regularly mobbed.
Anyway, it's Tuesday, so Carnage has broken out of Ravencroft again and is on yet another rampage. At the Daily Bugle, he attacks Robbie Robertson's wife but does not kill her. (This leads to a secondary subplot that ends Robertson ultimately leaving the Daily Bugle, which didn't last too long either)
The Silver Surfer's in town mainly because he wants to welcome back the Fantastic Four who have returned after being killed by Onslaught.
The Surfer responds that he is in fact familiar with their kind and, stating that the entire world is at risk, goes into the sewers to pursue it.
So Spider-Man battles the Carnage Cosmic for a little bit before the Silver Surfer gains enough control to flee into space to battle the symbiote there.
Meanwhile, Spider-Man takes Kasady to the hospital, where it's revealed that he's suffering from an advanced stage of stomach cancer and that the symbiote was the only thing keeping him alive. Spider-Man wonders if it would be murder if he were to prevent the symbiote from reuniting with him, given how many innocent lives Carnage has taken.
So Spidey and the Surfer head off to Cletus's hospital room, where the symbiote once again bonds with its host.
Of course, in the true Marvel fashion, this was ignored the next time Carnage appeared and hasn't been referenced since.