The return of Captain Cold and Heatwave
Arrow and Flash set out on a mission to try and find people like them but in selfish and bad way. The flash comes across with Deathstroke for the first time "long time Deathstroke I thought you was dead" said arrow "how can I die when I'm already dead" before both flash and arrow could attack Deathstroke he was gone in a second. The Flash tried to use his superspeed top catch him but Arrow said "no we are no after him, I will get him later, he is not important right now, we need to find Captain Boomerang before he kills anyone."
After they both had lunch at Barry Allen's crush Iris's café they both set out to search for Captain Boomerang. Looking high and low, both Arrow and The Flash saw two people playing with gun that was heating and freezing people. The flash recognise who the man was with the freezing gun, both Arrow and The Flash had to go to fight another metahuman called Kyle Nimbus, a.k.a. The Mist, a dangerous new meta-human with toxic gas powers.