Clinging to a semi-precarious existence in TriBeCa, Corrine and Russell Calloway have survived a separation and are wonderstruck by young twins whose provenance is nothing less than miraculous. Several miles uptown and perched near the top of the Upper East Side's social register, Luke McGavock has postponed his accumulation of wealth in an attempt to recover the sense of purpose now lacking in a life that often gives him pause. But on a September morning, brightness falls horribly from the sky, and people worlds apart suddenly find themselves working side by side at the devastated site.