In Milwaukee, Wisconsin, The police and news gather when a bank is robbed and the thieves hole up inside. One of the hostages is forced outside... by Dean.One Day Ago
Sam and Dean pose as FBI agents to investigate a jewelry store robbery. The head buyer, Helena Smith, went berserk, shot a guard, and stole the safe's contents, and then went home and killed herself. As the store manager points out, it made no sense for her to rob the store, hide the jewelry, and then commit suicide. The police took all of the security footage tape.
After they finish their interviews, the brothers go to the home of a Ronald Resnick, who was a security guard at a bank that was robbed using a similar MO a month ago. When they knock on the door, high-beam lights come on. Ronald checks their badges and then insists that he already gave his statement to the police. However, he's surprised when they ask for more details. He invites them in and tells the brothers that he told the police there was more going on. The suicidal robber, Juan, was a friend of his who came to the bank to play cards. Ronald insists that the person he let into the bank wasn't Juan, but someone who looked like him. He also knows about the jewelry store robbery and figures the same robber is involved, and he's a shapeshifting robot like a Terminator, a Mandroid. When they wonder what evidence he has, Ronald explains that he made copies of the security tapes and shows them to the brothers. On the tapes, Juan has "laser eyes," and the brothers realize that they're dealing with a shapeshifter. Ronald says that he plans to hunt down the shapeshifter, and he's traced the pattern of robberies to its underground lair. Sam tells him there's no such thing as Mandroids and the laser eyes are camera flare. An angry Ronald orders them out, and Sam takes the tapes first.
Back at the motel, Dean notes that Ronald did good work and is like them, but Sam warns that Ronald is no professional and the shapeshifter would easily kill him. Dean compares the robberies to the sewer lines and finds one more bank on the same line, the City Bank of Milwaukee.
Sam and Dean pose as members of the security company and the friendly bank guard escorts them to the monitor room. The brothers check for lens flare but spot nothing at first, and Dean focuses on the female tellers. However, they finally spot the bank manager with glowing eyes. As they start to go after the shifter, they see Ronald come into the bank and rig chains to the doors. He then takes out an assault rifle, fires into the ceiling, announces he's not a robber, and orders everyone down on the floor.
Sam and Dean try to approach Ronald and Dean does the talking. Ronald orders them to get down and demands to know who they really are. He orders a customer to frisk Dean and the man finds a silver knife. After Ronald has the customer throw it in a deposit slot, Dean calls him over and tells him that the bank manager is the shifter. However, Ronald figures that Dean is lying to stall. Dean tells him that they're running out of time and offers himself as a hostage. Ronald finally agrees and orders everyone else into the vault while Dean comes with him.
The police soon realize that the bank is locked up and surround the place.
Ronald has Dean escort everyone into the vault and close the door. The two men start searching the offices and Ronald slips on the shifter's discarded skin. Dean realizes what that means, that the shifter has taken on a new form, and explains that the shifter is human, not a robot. He finds a silver letter opener and explains about the shifter's vulnerability.
SWAT teams mobilize outside as the news crews arrive. Lt. Robarts takes command and gets an update on the situation. He orders his men to cut the power.
Ronald admits to Dean that he's happy that he's been proven right. The lights go out and Dean realizes that the police have surrounded the buildings. He warns Ronald that the cameras are out as well, meaning they can't locate the shapeshifter by the lens glare.
In the vault, one of the tellers, Sherri, keeps asking Sam questions about his wonderful brother. They're interrupted when Dean opens the vault door, but only to escort a few more hostages in. He then calls Sam out and closes the door, much to Sherri's chagrin. Dean tells his brother what they've found, and Sam wonders how they'll get out given that Dean is wanted by the police. Dean says they'll deal with that later and right now they need to find the shifter. As he gives Sam another silver letter opener, Dean says that they can't let the police in because they'll arrest all of them and the shifter will get away. Dean goes to search while Sam stands guard with Ronald, and hears something.
The hostages start to panic, and Dean opens the vault to let some air in. Sherri asks why he's helping Ronald, while the bank guard starts to have a heart attack. The phone rings and Ronald answers, and muddles through a conversation with the police. Sam finally hangs up the phone on Ronald and tells him that they need to keep a low profile. The other hostages insist that the bank guard needs help, but Sam suspects a trap. However, he calls Robarts and says that he needs to send in a paramedic.
Dean checks the offices and notices a loose ceiling tile. He nudges it with a coatrack and the corpse of one of the hostages falls down.
The shifter hostage demands that Sam release them, and Ronald draws on him. Dean returns and tells Sam what he's discovered, and Sam escorts the bank guard out. Dean eyes the shifter hostage for a moment and then invites him out. The shifter comes out, knocks Dean down, and runs for the offices. Ronald chases after him, freezes for a moment in the outside lights, and a sniper shoots him in the back while Sam and Dean look on in horror.
Sam tells Dean to get the bank guard outside while he goes after the shifter. Dean crawls over to Ronald and apologizes, admitting he did a good job. He then grabs Ronald's rifle. Meanwhile, Sam searches the offices and stumbles across Sherri and the other hostages, who have exited through the open vault door. He orders them back to the vault for their own safety.
Dean escorts the bank guard to the door and sends him out, and then closes the outside door and locks it.
Sam finds more discarded shifter skin in the stairwell and calls Dean, and then goes to search the place.
The FBI arrives outside, much to Robarts' disgust. Special Agent Victor Henricksen takes command, but Robarts warns that things aren't normal. Henricksen insists that there's a monster in the bank.
Sam searches the bank while Dean gets the hostages back into the vault. Sherri admits that she's disappointed in Dean, thinking he was a good guy. The phone rings and Dean takes the call. It's Henricksen, who says his job is to bring Dean in and knows him and Sam by name. The FBI agent explains that he knows about everything they've been up to, and their wacko dad. Henricksen gives them one hour to surrender or they'll come in shooting. However, once Henricksen hangs up, he tells Robarts that they're going in five minutes. When Robarts disagrees, Henricksen insists that Dean and Sam are the greater danger.
Sam finds a blood trail and follows it to an office containing Sherri, her throat cut. He goes to the vault and tells Dean what he's found. They open the vault door and tell Sherri they're releasing her, but she hesitates and says that she wants to stay with the others. She notices Sam covertly holding the letter opener but goes outside with them. They then show her the Sherri corpse and she screams in terror... and then faints. Dean prepares to kill her anyway, but Sam points out that there's no advantage to it fainting. After a moment, Dean goes to the "corpse." Before he can do anything, there's a crashing sound from the lobby. The "corpse" comes to life, attacks him, and runs out of the office.
The SWAT team enters the bank and fan out to search the place. They find Sherri, who begs them not to search. As they get her out, they find one of the brothers and tell him to freeze.
Dean searches the basement and finds the electrical closet. Someone attacks him and knocks him down.
The SWAT team moves in on Sam, who knocks them out.
The Sherri shifter attacks Dean and they grapple. Dean is distracted when he pulls some of the skin off of its arm. It kicks him in the groin, but he manages to recover and stab it in the stomach, killing it. As he starts to pull the letter opener out, a SWAT soldier comes in and shines a light on him.
Henricksen enters the bank and discovers there are two corpses... and one is of a hostage they just walked out of the bank. His men find no sign of Sam and Dean. Roberts' man, Sgt. Tucker, tells him that they've found two unconscious SWAT soldiers, stripped of their uniforms.
Dean and Sam sneak out, wearing the uniforms, and escape in the Impala. Dean figures that they're screwed.