A lot of the times now, I think, "The Orthodox Church" and "The Orthodox Way" by Met. Kallistos are combined into one book called "The Orthodox Church." Mine came that way, I think.
But I think to get a really good answer you'd have to give us a bit more of a profile of this person. For example, for my mom I'd recommend "Facing East" by Kh. Frederica Mathewes-Green, because my mom isn't going to be interested in theological or heavily historical discussion, but will enjoy the narrative of a woman telling a story with some teaching thrown in, and like the examples of Orthodox community in that book. For my dad I'd probably give The Rainbow Series, because that goes far more in depth and he'd enjoy the theological differences and short chapters. For my cousin Jason who's a protestant pastor I'd probably go with "Common Ground" by Jordan Banjis because it operates from a Western perspective showing how the East differs, without being confrontational but without denying anything. For some people I've just given prayer books, and they learn about Orthodoxy from the prayers we pray.
So what sort of person are you asking for, and what sort of book? Do you want a story, something focused on the spirituality, the theology, the history? What denomination is the person now, and why do they want to know about Orthodoxy?