The Flash 4×17 “Null and Annoyed” Season 4 Episode 17 Sneak Peek – DANNY TREJO RETURNS AS BREACHER; KEVIN SMITH DIRECTS — Barry (Grant Gustin) and Ralph (guest star Hartley Sawyer) take different approaches to finding the remaining bus metas before DeVoe gets to them. However, Ralph’s cavalier attitude frustrates Barry and the two clash over what it means to be a hero. Meanwhile, Breacher (guest star Danny Trejo) returns to ask Cisco (Carlos Valdes) for a favor. Kevin Smith directed the episode written by Lauren Certo & Kristen Kim (#417). Original airdate 4/10/2018.