The Flash Season 2 Episode 17 did not lack for exciting storylines.
Most notably, Barry grew especially determined to get back to Earth-2 in order to stop Zoom.
However, he realized that he needed to increase his speed to accomplish this important goal.
Therefore, he went back in time and masqueraded as his earlier self to get his arch-nemesis Dr. Harrison to teach him how to run faster.
But while there, Barry faced familiar nemesis Hartley Rathaway ... along with an old friend in Eddie Thawne.
Confused? Intrigued? Sit back and watch The Flash online for this all to make more sense.