It beings by talking about clues or hints or voices that seem to call a person to something. The four 'voices' in the book are 1) the call for justice, 2) the call for things spiritual, 3) relationships and 4) beauty. The author makes very good arguments on how these callings seem to point to something beyond ourselves.
The book then moves on to talk about worldviews and how the Christian worldview makes the most sense of the things we see and feel. He talks of the history of Israel and how thing were pointing to Jesus. The bulk of the Christian story is discussed in the following chapters.
I highly recommend this book and I'll be rereading it again.
I might add the the points on 'relationships' relates very well with the Donald Miller book called 'Searching for God Knows What' which I'll post on later.