Esra (Hazal Kaya), a young orphaned journalist in modern-day Istanbul, is assigned to write an article about the upcoming 130th anniversary of the Pera Palace Hotel. At the hotel, she meets its manager, Ahmet (Tansu Biçer), who shows her around and explains the history of the Pera Palace and some of its famous guests. Esra is particularly intrigued by the story of Peride, a young woman who apparently saved Mustafa Kemal from an assassination plot orchestrated by the British in 1919, during the occupation of Istanbul.
What Ahmet conceals from her is that, in combination with a mysterious key, one of the hotel's rooms becomes a time-travelling portal. That night, Esra accidentally time travels back to 1919, where she is soon mistaken for her apparent doppelganger, Peride. Her encounters with men such as George, a scheming British officer (James Chalmers), Halit, an enigmatic nightclub owner (Selahattin Paşalı), and Reşat, a police officer in love with Peride (Engin Hepileri) leave her struggling to know whom to trust. Together with Ahmet, however, she must find a way to stop the assassination attempt on Mustafa Kemal and preserve the course of Turkey's independence.