Kristine Kathryn Rusch 
September at Wall and Broad [EPUB ebook] 

September 1920, New York City: Phillipa D’Arco makes a living investigating the past for the United States Government. Bloodless, they call her, making her one of the best operatives. So, when Phillipa fails to return back to 2057 to report her findings, Assistant Attorney General Preston Lane needs to make a decision: send in yet another investigator or lose a valuable asset.

Whatever Lane decides, he knows he’ll face consequences. But the truth behind Phillipa’s disappearance will cause ripples in time Lane can’t begin to imagine.

’Rusch writes humanist SF.’