who pushed zoe barnes off the platform?
At the end of the first season, Lucas, Zoe Barnes, and Janine Skorsky had been investigating the murder of Congressman Peter Russo. Primary suspect: Frank Underwood, whom Zoe had been sleeping with to gain political access and further her career. Doug Stamper, Frank's henchman, learned of their investigation and warned Frank, who then pushed Zoe off a train platform to her death. Janine received nude photos of Zoe in her mailbox, and was understandably spooked. She fled to Ithaca, New York, to live with her mother.