Graeme Goldsworthy's According to Plan: The Unfolding Revelation of God in the Bible (IVP 1991) is a very helpful introduction to biblical theology, to reading the whole Bible as a unified story culminating in Christ. For someone not yet convinced, or only fuzzily, that the Bible is a single story with a single Hero, this is the place to start, and to encourage others to start. It is more substantive as well as more satisfyingly christocentric than Alexander's From Eden to the New Jerusalem, less focused only on individuals (and a bit less preachy) than Clowney's The Unfolding Mystery, more accessible than the massive tomes trying to do similar whole-Bible theologies such as Geerhardus Vos' Biblical Theology or Charles Scobie's more recent The Ways of Our God, and is all focused on the beginner--for example, there are zero footnotes, terms like eschatology and biblical theology and covenant are defined, and dozens of charts clarify his ideas. (These other works are, however, all very helpful too, along with, in particular, Bavinck, Beale, Poythress, Greidanus, and Gaffin.)
Most importantly, Goldsworthy is clearer than anyone else I've yet come across in showing two things: (1) that Jesus is the meaning and fulfillment and integrative center of the biblical narrative; and (2) that the gospel is central to the message of the Bible and that this gospel ought not to be confused with its corollaries (such as faith and repentance, etc).
Here's a good representative statement with regard to (1).
Significant figures, such as priests and kings, who mediated salvation for the many in Israel, point to the One who comes as the true Israelite representing the many. On the basis of this interpretation of the prophetic promises, the Jews were waiting for a return of a great crowd of people to the Promised Land. Even the remnant would be a considerable group. They were not prepared for the true people of God to be one man. They could not see that everything that God had intended for Adam and then for Israel was being fulfilled in the perfectly sinless human existence of Jesus. (204)