What is the fine-grained topic of the following text: Nora blackmails her cousin Riley, into riding with her on the Cyclone, the Coney Island amusement park’s famous roller coaster, and as soon as they get off Riley collapses from a stroke and is hospitalized, partly paralyzed and nearly unable to speak. Only return the topic.
Riley having a stroke after riding a roller coaster at Coney Island amusement park