A villain named Leonard Snart gets his hands on a "cold gun" - which could kill the Flash. Felicity Smoak drops by for a surprise visit and Joe gives Iris the silent treatment after finding out she's dating his partner, Eddie Thawne. Meanwhile, Barry tries to stop Captain Cold from robbing a bank, but is too slow to save a man after getting blasted with the cold gun. At the end, the two have a final epic confrontation by the train tracks.
To be extended
Felicity warns Barry not to run too fast lest he be turned to dust. This is a direct reference to The Flash's death in in the comics Crisis on Infinite Earths.
The 'Rogue' part in the title refers to The Flash's "Rogue Gallery" which is, in the comics, a group of supervillains that usually repeatedly return to try to take down the scarlet speedster.