Bolin, Mako, and Asami are now prisoners for standing against Police actions against Non-Benders. This was after Tarrlokk got a law passed in which all Non-Benders to go under a curfew. This shuts down their power in their homes at a certain time. A non-bender protest happens and it's mistaken for an Equalist rally. Korra and her friends showed up to defend the innocent Non-Benders. This leads to some of them being arrested. While Korra is left alone.
After which though Korra takes action herself by meeting with Tarrlokk one by one and fights him. She overpowers him quite easily especially when there's no longer any water for him to bend... Or so she thought. Tarrlokk bloodbends Korra and uses it to weaken Korra and is now taking Korra to somewhere outside of Republic City.
Also it turns out all those visions were possibly Aang trying to tell Korra something. Oh man this is getting exciting :D