Increment

Ignatius, David. (2009). The increment. New York: W.W. Norton.

A nuclear scientist with a conscientious objection to the regime ruling Iran pursuing a nuclear weapon contacts the CIA through its website. A virtual walkin, or VW, he comes to the attention of Harry Pappas, an agent with his own conscience who wants to stop the Administration from hurtling toward imposing an embargo on, and perhaps bombing, Iran.
     Ignatius writes a believable tale, an enjoyable what if?

One review in the Washington Post offers a compliment: It may lack fireworks, but it bears the hard weight of both political and personal history and recognizes the seriousness of what might come next.
One in the Guardian is a bit more reticent: well paced and suspenseful, and the attention to local detail (downtown Tehran is rendered as vividly as top-level CIA briefings) convincing enough to excuse the occasional stereotype.