<Tr> <Td_colspan="8"> Klaus and Stefan arrive in Chicago, where they knew each other during one of Stefan's previous periods as a Ripper in the 1920s . It is revealed that Klaus knew Stefan in the 1920s . Stefan met Klaus and Rebekah in a bar where they became close . Klaus and Rebekah had to leave and Klaus compelled Stefan to forget them . Klaus then daggers Rebekah . In present day, he removes the dagger keeping her demobilized as she has what Gloria (a powerful witch) needs to help Klaus create hybrids . It is revealed that what Gloria needs is the necklace Stefan had given Elena . Damon gets a tip on Stefan and Klaus' whereabouts from Katherine so he and Elena follow the trail . They go to Stefan's old apartment, where Elena sees Stefan's list of victims . While there, Stefan and Klaus arrive . Stefan sees Elena, however doesn't tell Klaus. Tyler tries to rescue Caroline, who is being tortured by her father, who believes he can change her urge to feed on blood by burning her in sunlight every time she feels the urge . </Td> </Tr> <Tr> <Th> 48 </Th> <Td> </Td> <Td> "Disturbing Behavior" </Td> <Td> Wendey Stanzler </Td> <Td> Brian Young </Td> <Td> October 6, 2011 (2011 - 10 - 06) </Td> <Td> 2J6004 </Td> <Td> 2.63 </Td> </Tr> <Tr> <Td_colspan="8"> In Chicago, Klaus uses Gloria the witch to find out why his hybrids aren't turning out the way he planned and Gloria discovers that Stefan is hiding the fact that the doppelgänger is still alive . She tortures Stefan, but Katherine saves him . Back in Mystic Falls, Damon changes his attitude and kills Alaric but Alaric comes back to life . Damon then tries to kill Bill . Caroline saves her father by giving him her blood and has a confrontation with Damon . Meanwhile, Bonnie returns to Mystic Falls and Jeremy tells her about seeing his ex-girlfriends as ghosts . Stefan also tries to find out what Klaus and his sister Rebekah are running from . The answer turns out to be Mikael . Katherine steals Elena's necklace that can contact the Original Witch and teams up with Damon . Klaus brings Stefan back to Mystic Falls to find out what he is hiding . </Td> </Tr> <Tr> <Th> 49 </Th> <Td> 5 </Td> <Td> "The Reckoning" </Td> <Td> John Behring </Td> <Td> Michael Narducci </Td> <Td> October 13, 2011 (2011 - 10 - 13) </Td> <Td> 2J6005 </Td> <Td> 2.89 </Td> </Tr>

When was season 3 of the vampire diaries filmed