The Arrow is hunting a criminal who uses Boomerangs into Central City. He and the Flash cross paths and the Flash and Oliver wants to train Barry to be a better hero. Meanwhile, a metahuman called Prism infects Barry with rage and maybe only Oliver can take him down.
This episode marks the first official crossover in the Arrowverse. And it was a decent episode though not the over the top action I expect from later crossovers. Still pretty good and I like the way they set it up so that Arrow and Flash can fight each other. The villain was a bit lackluster but the real emphasis was on setting up the Flash and Arrow fight. Which was really good but done a little too soon perhaps as the episode really peaks with the fight but still has ten minutes to eat up afterwards.
Outside of the last bit, this was a very exciting episode with some good tension and a very good fight between superheroes.
+10: Great episode, personally I love it when heroes fight each other
-1: Only eating up time at the end