This movie takes place soon after the events of the first movie, where the killer known as "the collector" is on a killing spree that's terrifying an entire city (but not enough to stop the kids from going to suspicious parties at creepy, weird locations in old buildings where they're sealed in by metal doors). Our partygoers soon encounter the collector, and he's clearly improved upon his killing gadgets from the first movie, because he kills a ton of people in nasty, disgustingly gory ways (but at the same time, we get to see friends crying for each other and trying to help each other escape, so there's a sense that these are REAL PEOPLE and not just heads in a body count. I like that shit).
So we're reunited with a character from the first movie who helps people search for a missing girl who's been abducted by the collector, and we get a deeper look into the collector's sick activities, plus we get to see a few heroic moves by badass characters who I actually liked and was rooting for, even though I knew they'd probably all die. Lee Tergesen plays one of these characters, and I like seeing him in movies, so that was fun. This was a great viewing experience for me, and I loved it.