This is not a new book. Far from it - it was first published in 1975. Yet a quarter of a century on it remains the most believable first contact story I've ever read. The plot is simple. An alien spacecraft appears in earth orbit, knocking out radar screens.
Governments panic and try to hide the facts.
When something from the ship actually lands in Montana, a team of scientists and the military charge in to investigate. The rest of the book is about their efforts to discover the facts whilst in the background international governments panic and prepare emergency measures. This is a very dry book. There's lots of science, lots of politics, lots of talk. This has the effect of making those scenes where there is action stand out even more vividly.