And no, it doesn't have anything to do with the fact that Eliza Duskhu makes her initial appearance in the episode brandishing a whip and wearing the sexy leather gear of a dominatrix.
Or not much, anyway.
"A Spy in the House of Love" involves Topher's surprising discovery of a spy inside the Dollhouse, one who can tap into his high-tech imprints and alter them without his knowledge. The NSA is suspected to be behind the secret mole, and one fast-paced portion of the episode concerns an Alias-like infiltration of that national agency by a disguised Sierra. But actually, the episode is structured cleverly to follow our four primary Actives as they go out on individual engagements, These Dolls are Echo, Victor, November and Sierra, and and each mini-adventure adds to the narrative of the main story at the same time that it builds good character touches.
In an act of self-preservation, Echo volunteers, for instance, to be imprinted as an expert interrogator, one who eventually brings down the spy. As I mentioned above, Sierra goes on a dangerous assignment at the NSA. November, meanwhile, unwittingly carries information for the spy inside the dollhouse to a bewildered Ballard (Penikott).
Finally, Victor's semi-regular, "a lonely heart," turns out to be the very woman running the entire show, De Witt (Olivia Williams). For the first time, we get to see the cracks in De Witt's shield: her loneliness, her isolation, her moral qualms about the Dollhouse and it's mission, and so on. You know the truism that it's lonely at the top? Well, De Witt has been living that for a long time, and secretly seeking companionship and solace with a Doll. The important thing is that this aspect of her personality gives us another layer to contemplate and sympathize with, something the druggie episode of a few weeks failed to accomplish.
The identity of the spy is revealed before the episode's denouement and the revelation is quite the shocker. I certainly didn't see it coming. I won't spoil it for you here, but let me say that it made sense, even if it seems to have arisen from left field. I also enjoyed the fact that this "mole" character and Echo launched into a brilliantly-orchestrated physical re-match (their first tussle was in "True Believer"); and that the much-discussed "attic" came into play during the finale.
Like Echo herself, Dollhouse is really and truly evolving. With Echo's dawning awareness, and the presence of several competing agendas and characters boasting hidden loyalties, the new Whedon series has at last ascended to a commendably complex, and highly-addictive level of storytelling. So yes -- after nine episodes -- count me officially as a fan.