Cameron takes a starring role in an episode that features very little Sarah, no Derek at all and John relegated to the B-plot (which, um, climaxes in a heavy make out session). So let's dispense with John and Riley right away. Riley? You're a psycho. And admitting that you're purposely trying to push John's buttons by flirting with another mom-hating douchebag doesn't make it OK. It makes you more of a psycho because you're doing it intentionally, and now John has to get into a fight because you think it's OK to steal someone's lighter.
So anyway, you know how Cameron likes to do super-fun crazy stuff like read the dictionary? Apparently she's read all the books at the Connor Compound, because she sneaks out at night to a library, where she befriends a guy who works the night shift, and she reads up on esoteric things.
A photo from a tragic New Year's party in 1920 catches her eye, and she recognizes one of the bystanders as a Terminator. She digs deeper, and we get to see a Terminator-with-a-Tommy-gun story that she manages to put together from records that are almost 90 years old. This terminator, Stark, somehow got sent to the wrong time; instead of going to 2010 to assassinate the governor of California ["Ha! Very clever." - Angel], he wound up in 1920. And here's how committed he is to seeing the mission through. When the owner of the building where he's to carry out his mission in 2010 refuses to sell back in the 1920s, Stark starts up his own construction company that eventually takes over the building (after some shady stuff like murder of the magnate's right-hand man), and Stark walls himself up to wait for the 21st century. Cameron gets to him first, and destroys him.
Which is great, because while she was out gallivanting around, Skynet got to the Connor Compound and killed everyone without Cameron there to guard them. Well, they didn't. But they could.
Well, looks like it's the 1920s, because everyone's dressed all flapper-style and listening to big band music. Really, did everyone dress like that then? Eighty years from now, if a show is set in the late nineties, is everyone going to be dressed in khaki and black and listening to the Squirrel Nut Zippers just because some people did? The happy carousing is cut short by this raging bonfire that has everyone screaming and running for the exits.
And they still look happier than John does, as we fade into the present day, with John farting around on a laptop in the dining room. He says he's dumped about fifty thousand websites, and there are hundreds of companies with three dots for a logo, including companies that make baby wipes and ice cream. "Nothing screams Skynet like baby wipes and ice cream," he says. Any new parent can change a diaper and figure that if such a sweet little bundle of joy can produce such a giant disgusting mess, then the end times can't be far off. John reminds her that she saw the three dots in a dream. Yeah, and also IN BLOOD ON A WALL, she points out, and tells him to keep looking. He says he will tomorrow, as he's beat. So Sarah passes off the laundry basket to Cameron and tells her to make herself useful, since she never sleeps. John isn't so tired that he can't hang around to sarcastically point out that Cameron is the most sophisticated killing machine ever invented, and she's got it doing laundry. Sarah's got the cure for that sassmouth: she takes the laundry basket and gives it John, who, once his mom is gone, sheepishly hands it back to Cameron, whose look clearly says, I may just be a terminator, but I know when I'm getting hosed. John walks out and turns the light out, so now she's got to turn on her nightvision just to fold the freakin' laundry.
And now Cameron's at the employee entrance of some university/library-looking building, and ringing the doorbell. The door's opened by a guy in a wheelchair who answers so quickly he kind of had to have already been there. Cameron holds up a bag: "One glazed, one rainbow sprinkle, one cinnamon twist." You never forget, do you, marvels the guy. I mean, it's THREE donuts. Does she need a mnemonic device?
So she's clearly been doing this a while; they sit in the library and work. Buddy asks her about her trip to Mexico, wondering if she met up with her friend. We flashback to Cameron and John digging up Chrome Artie but finding only a boot. "He was gone when we got there," says Cameron, and then agrees with Eric that it was "a bummer." Eric asks if her brother is still dating that crazy girl, and Cameron says yes, telling him about getting robbed because Riley snuck out the window. Eric asks if they got who did it, and Cameron flashes back to blowing away the perps in the bowling alley. "Everything worked out fine," she says.