So! What do you think the various world-leaders would do if a Near Earth Object (NEO) appeared in the sky? Heaven's Shadow is about that. Not surprisingly, the appearance sparks a contest between the US and the rest of the world to get to the object first. Two space ships are sent to investigate and they discover more than they had bargained for. The NEO turns out to be alien and not necessarily friendly.
Paranoia, curiosity and courage are all displayed along with pretty natural, yet often unwise reactions. Our perspective is from the NASA spaceship's crews - their actions and reactions.
This novel is a fun read. The way people act in it seems pretty realistic. The whole alien NEO thing not so much. But that's what SciFi is, likely and unlikely thoughts about the future. What is likely is that at some point in the future an NEO could come close enough for us to visit. That's what makes it so fun to read. Knowing part of the story could possibly happen given a certain set of circumstances.