Riverdale's KJ Apa is heading back to the big screen. Deadline reports that Apa has joined the cast of Gulfstream Pictures' romantic comedy, The Last Summer. Apa, who plays Archie on The CW's Archie Comics-based drama series, will play the fil's lead role, Griffin. The Last Summer follows a group of high school graduates whose lives intersect in Chicago over the summer before they go off to college.