Chloe introduces us in the beginning, by a video she made -- judging on her clothes and hair, sometime around Whisper, possibly in Covenant. "I don't even know where to start. I know you must have a million questions, but I don't know how many answers I can give you." We pull out to see her cousin from Delete watching them in the Torch. Chloe continues: "If you're watching this, it means I'm probably dead. You were always the one good thing in my life, and if I didn't tell you enough, I care about you more than you'll ever know. Please find out who did this, Clark. You're the only one who can."
Of course, Clark is missing which means we spend most of the episode following her cousin around, even to meeting Lionel Luthor where her cousin wrongly deduces that he wasn't behind Chloe's death (which confirms later in the next episode that he was). We also see brainwashed Clark, Kal-El, staring briefly at a picture of Chloe and Lana.