We begin in Berlin. A nude blonde is in bed with a man. The woman tells the man that when we're done here maybe they should go back to Fiji. He agrees, and then gets out of bed to take a shower. AS soon as the water starts, she hops out of bed and races for a laptop to send a message. The shower is empty. We hear a door creak. The woman pulls out a gun. The water is still running. She creeps down the hall. Discovers the empty shower. The guy punches her. The guy calls Sloan. He reports that he has been compromised. Something he said. Sloan instructs that he should send a message back by the woman.

Los Angeles - Sid watches the cleanup at SD6. Vaughn comes in says he heard she was here. Sid couldn't sleep; she thought it was a dream. Marshall and Dixon are in debriefing for a while. Sloan is on Interpol's most wanted list. Sid and Vaughn are all smiles at each other. Sid brings up last night. Vaughn says they aren't together anymore (referring to Alice). Vaughn says that they have been over for a long time. More grins. Sid says she can actually go to the CIA through the front door. Vaughn gushes and I can actually give you a ride.

Back in Berlin - a van careens around a corner, dumps the woman out on a street corner. She appears to be wrapped in explosives. People run.

Los Angeles - Enter Christine Phillips a new clandestine service graduate who is going to be observing. Weiss introduces her to the group. Christine tells Sid that she's read her operational file; it's a real honor.

Berlin, the police arrive.

The CIA is apprised of the Berlin situation. Weiss says that's agent Wallace. It's one of theirs. Kendall says to check the explosives. It's C-4. Any radio communication could set it off. The man tells her via radio that she is doing fine. A German police officer says something in German. The put Sid on the phone to the German police to tell them that any radio communication could set it off. As the German police officer comes close. Wallace begins singing "Pop Goes the Weasel."

CIA watches this via television. Wallace continues singing. She cringes each time she says pop. Sid reaches the police. They have already ordered radio silence. Wallace says pop again. The bomb explodes.

Sid rinses her face off in the ladies room. Christine is in there crying. Sid asks if she is okay. Christine says that she wasn't ready for that.

Kendall briefs the team. Wallace was in deep cover. She was attempting to gain the trust of Dr. Renzo Marcovich. Who was in charge of a project that several terrorist organizations were bidding on. Wallace was sent in with a partner. They don't know what happened to the partner. He is presumed compromised or dead. Marcovich was last seen heading for the Dominican Republic. Sid is going in. Vaughn is going to help. The agent is James Lennox (aka the man from our earlier scene with the woman).

Vaughn arrives at Sid's. They're still doing that goofy grin thing. This is Vaughn's first time of seeing Sid's place. They kiss again. Fake Francie walks in. Sid introduces him.

Cayo Concha with music by The Cars. Sid gets out of a pool in a blue bikini. She towels dry and catches the eye of a man. Presumably, Marcovich's security head. Sid walks into a cabana taking her bikini top off as she goes. Security head falls for it, follows her. He enters the cabana and comes face to face with Vaughn as well as Sid. Sid holds him down. Vaughn injects him with something that will give him a heart attack within the hour if he doesn't receive the antidote. Cooperate, and they'll give him the antidote.

They ask if Lennox is still alive. Security head says yes and gives a room number. Sid, in disguise and Vaughn go with the Security guy upstairs. Sid separates from the other two. Vaughn (on their trip) warns that Lennox could have undergone psychological conditioning. It could be a trap. Sid comes in during the middle of a torture session. Sid takes out the torturers and rescues Lennox. Lennox can't see - they were using a photo reactive acid. Sid bandages Lennox's eyes. Security guy gets Vaughn into the computer system. Vaughn knocks him out and administers the antidote. Sid and Lennox meet up with goons in the hall. Sid fights them. Lennox's bandage comes off. He shoots a guard trying to kill Sid. Sid rushes Lennox off.

On the plane she administers mediation to help him. Vaughn asks Sid if he's okay. No signs of psychological trauma. Sid says he was holding his own against the interrogators and about to lose his sight. Lennox looks at Sid and tells her he thought she was a blonde. Sid says it's normally brown but hard to keep track. Lennox asks where Emma (Wallace) is. Sid tells him that she's dead.

Kendall talks to Lennox along with Sid, Jack and Vaughn. Lennox says he and Wallace were brought in as freelance security experts. Wallace was his driver. She was privy to a call between Marcovich and potentially his superior. He indicated that Helix was ready for testing. Lennox never heard the voice of the supposed superior himself. Lennox went in to Cabo Concha alone to transmit the data to Wallace if he was caught. Kendall ends the debriefing. Wallace says that they were engaged.

Weiss explains to Christine that they digitize all the news footage. He slips in asking her to dinner. She quickly responds with I have a boyfriend. Vaughn talks to Weiss. Wallace phoned in every 2 days like clockwork. The day Lennox talks about, nothing. No extraction request, nothing. Christine watches the footage again. She notices a flash right before the explosion. An RF (radio frequency) transmitter would account for it, but all radios were off. Weiss watches. He gets Christine on tracing down all television crews etc. Whatever set it off had to be within a block. Whatever set it off had to be within a block.

Sid goes to Lennox's. She goes inside. Lennox is sitting in the kitchen in the dark. He has been drinking. Sid tells him she lost her fiancé last year. That they were trained to compartmentalize things that make them hurt. But she hasn't been able to (okay, complaint time - and this is the same chick that at the beginning of the program was making goofy smiles at Vaughn?) Lennox and Sid kiss (see my previous comment). Lennox backs off and says he's sorry. Two men come in calling for Bristow and Lennox. Sid and Lennox overpower them. Lennox tells Sid to go. The men grab Lennox. He's going to be placed in federal custody.

Sid arrives at HQ. Jack tells Sid that the decrypted the information. Helix is a next generation molecular project. A patients face and body are molded to look like someone else. Lennox was a first patient. Lennox may not be Lennox. The first recipient was Marcovich. Vaughn shows Sid the footage of Lennox in a phone booth at the explosion.

Jack briefs the team. Men like Osama bin Laden could hide. There are no scars. It only works on people with a specific genetic disposition. The only way to tell them apart would be to perform an ocular scan. A flaw was built in. Sid tells Lennox that he's been doubled, and that the recipient was Marcovich. Lennox realizes that Wallace thought she was still with him. Sid is going in to destroy it. Lennox is going with her.

Vaughn apprises the pair of guard's locations. They take out the guards in a rail yard. They lose the last guard's signal. Sid shoots him. Lennox drills into the side of a rail car. He's having trouble seeing the third tumbler. They crack the lock and gain entry to the car. Sid goes to rig the explosives. Lennox goes to send the schematics to the CIA. Lennox says that the sequence has been used twice. He's not the only one who has been doubled. It doesn't say. WE morph to a Francie, then to Vaughn at CIA. It is Lennox saying that the man they rescued was Lennox - who is calling from a cell phone in Poland. Jack thinks it may be Marcovich. Cell phone Lennox says that the ocular scan was disinformation. He wanted them to trust him. Cell phone Lennox reaches the rail car.

Vaughn reaches Sid on a separate channel. He tells her not to take her eyes off the man she's with. Jack tells Sid to disarm the man she's with, take cover then disarm the other man and bring them both back. They'll sort it out then. Sid disarms railcar Lennox. Cloud cover obscures the CIA's ability to track people in the rail yard. Railcar Lennox pleads with Sid that he's the real one. And that they other one is fake and wants them to not destroy the car. Sid finds cell phone Lennox outside the rail car. He recognizes that she's CIA. Cell phone Lennox tells Sid to get down. He fires at rail yard Lennox. Both Lennox's and Sid are in the rail yard with guns. We have a face to face with both Lennox's. Sid drops her weapon. She pulls out the detonator. Tells Marcovich she hopes he likes his face, he'll have it for a long time. The fake Lennox tries to shoot her. The real Lennox shoots the fake Lennox.

Back in Los Angeles, Lennox talks with Vaughn. He has 4 weeks off. He's going to Fiji. They were going to go to Fiji for their honeymoon. Sid says she knew. She knew Wallace. Sid tells Lennox that she was lucky to have known her fiancé for as long as she did. Then we morph to Sid drinking wine and cooking with Vaughn watching. Sid and Vaughn kiss. Sid says dinners ready. Vaughn says there is a microwave - they can reheat. And bedroom. Close up of the television in Sid's room. Which how has a camera on it. Fake Francie watches Vaughn and Sid mess around.