We open with a flashback of Caroline joining (or being strong-armed into?) the Dollhouse. She's offered the 5 year plan. She was an animal rights activist who was working to expose the practices of the Rossum Corporation, a pharmaceutical company. And I'm guessing that, to shut her up, they threw her into service in the Dollhouse.
Rossum is involved in the Dollhouse somehow, maybe backs it financially or something? But they need help now - they're working on a drug that has gone missing from the Rossum Building on a college campus and they need a team of Actives to find it. Also, a drug that turns people all goofy is leaked. I love a good drunk/drugged-up, watch-all-the-main-characters-get-high episode. Echo's Handler gets loopy, Close-Eyes too, even Topher strips down to his underwear while the British chick jumps on a trampoline.
The drug makes the Actives glitch, meaning they have traumatic memories of their pasts, Engagements and real.
Echo's on another Engagement when she sees news footage of the campus. This brings forth some memory and she leaves to go to the campus. She follows her vague memories to break into the Rossum Building with another student. She remembers breaking in with her boyfriend, who got shot by security and died.
In the final flashback we see that Caroline did indeed get forced into a deal with Rossum/the Dollhouse because she "fit the profile." And now, in the present day, they offer the same deal to the Hot Shirtless Black Dude who helped Echo break into the Rossum Building.