When no one is watching : a thriller

"Sydney Green is Brooklyn born and raised, but her beloved neighborhood seems to change every time she blinks. Condos are sprouting like weeds, FOR SALE signs are popping up overnight, and the neighbors she's known all her life are disappearing. To hold onto her community's past and present, Sydney channels her frustration into a walking tour and finds an unlikely and unwanted assistant in one of the new arrivals to the block--her neighbor Theo....