Eric Foner’s Gateway to Freedom.
Actually, I don’t recommend this book. The New York Times does. I haven’t read it yet. But I will because (1) Eric Foner admitted me to the graduate program in history at Columbia (and I’ve forgiven him for losing my only copy of Joseph R. Holmes’ photograph), and (2) in the 1930s, Ardeanur Hart worked for a descendant of Sidney Howard Gay at the family’s Staten Island house, formerly an Underground Railroad station.
Scuffalong: Genealogy. 
Dear Ms. Henderson,
Have you had you heard about Secrets of the Underground Railroad in New York City, Sydney Howard Gay, Louis Napoleon and the Record of Fugitives which I co-authored with Tom Calarco?
Our book came out shortly after Gateway to Freedom. Secret Lives is very different than Gateway.
We are having very positive responses.
No, I hadn’t, but thank you for bringing it to my attention!