The Flash 3x21 Promo/Preview "Cause and Effect" The Flash Season 3 Episode 21 Promo The Flash 3x21 Promo "Cause and Effect" (HD) The Flash 3. sezon 21. bölüm fragmanı » Starring: Grant Gustin, Candice Patton, Danielle Panabaker, Carlos Valdes, Tom Cavanagh