When advertising artist Si Morley is recruited to join a covert government operation exploring the possibility of time travel, he jumps at the chance to leave his mundane 20th-century existence and step into the past. But he also has another motivation for going back in time: a half-burned letter that tells of a mysterious, tragic death and ominously of “fire which will destroy the whole world.” Traveling to New York City in January 1882 to investigate, he finds a Manhattan teeming with a different kind of life, the waterfront unimpeded by skyscrapers, open-air markets packed with activity, Central Park bustling with horse drawn sleighs—a city on the precipice of great things. At first, Si welcomes these trips as a temporary escape but when he falls in love with a woman he meets in the past, he must choose whether to return to modern life or live in 1882 for good.