Nightshifter

Nightshifter has Sam and Dean up against another shapeshifter. Their first encounter was in the season one episode, Skin.

Sam and Dean investigate a string of robberies where it looks like employees rob various institutions (jewelry store, banks, etc.) stash the pilfered items and then commit suicide.

They talk to Ronald Resnik, a bank employee whose friend, Juan, robbed the bank. Ronald tells Sam and Dean that his friend did not rob the bank but a "mandroid" that looked like his friend. Ronald tells Sam and Dean that if the authorities won't do something about the "mandroid" then he would. Sam tells Ronald that there is no such thing as "mandroids" and that his friend robbed the bank, end of story. When Dean asks Sam about why he was so harsh, Sam tells him "better to stay in the dark and stay alive."

They figure out which bank that the shapeshifer may hit next, so Sam and Dean pretend to be security camera technicians in order to spot the shapeshifter. Right after they spot it, Ronald shows up, locks the bank and pulls a gun on everyone.

Sam and Dean try to calm Ronald down but it doesn't work. Dean finally tells Ronald that the bank manager has the "laser eyes". Dean talks Ronald into taking Dean as a hostage while everyone else gets into the vault. Dean and Ronald find the shed skin of the shapeshifer which makes tracking it harder. Dean also tells Ronald that its not a "mandroid" but a shapeshifter and that silver is the only thing that will kill it. Meanwhile, the SWAT team is called to the bank since they think its a robbery.

Dean is trying to keep everything in check but Sam freaks out when he realizes the cops are outside, considering Dean is wanted by the police. The situation goes from bad to worse when Ronald gets shot and an FBI agent, Victor Hendrickson shows up on the scene and he knows an awful lot about Dean, Sam and John Winchester.

The clock is running out and the shapeshifter is always one step ahead of Dean and Sam. They think that the shapeshifer is masquerading as a young woman that is with the other hostages in the vault but come to find out that the shapeshifter actually made itself look like the dead woman. Dean fights with the shapeshifter and stabs it with a silver letter opener. Okay, one problem solved, now to figure out an escape plan.

The SWAT team enters the bank, searches the bank for Sam and Dean and just when you think that this is the end of the road for the Winchesters, they escape by attacking two SWAT team members and stealing their clothes.

The song Renegade by Styxx plays as the last scene shows Dean and Sam making their way to a parking garage where they parked the Impala. Dean sums up the entire situation in one sentence: "We are so screwed."