Deus Ex Victoriana

 New York City: The Year is 1889.
New York City: The year is the future.
In 1888 a group of bold pseudo-scientists discover the "temporal current" and begin to view the distant futures that await the Empire City. In the future, all life as we know it has crumbled, leaving New York City a ghost town with a populous scrabbling to survive underground.
In the past it's up to an unlikely group of Victorian heroines and heroes to preserve something of their world to save their future generations.
In the future it's up to an unlikely group of future survivors to take a leap of faith; discovering what their ancestors left for them with no more guarantees than love and hope.