Thad Roberts had a plum spot in an elite NASA internship program and the respect of peers and scientists. So what possessed him to risk all that to steal and sell moon rocks?

Ben Mezrich seeks to answer that question in "Sex on the Moon: The Amazing Story Behind the Most Audacious Heist in History," an absorbing account of the 2002 crime of the Space Age. Mezrich wrote the book behind the hit movie "The Social Network" and brings that cinematic touch to another off-balance character study. This time he profiles Roberts, a young man way too sharp for his own good.

We meet Roberts as he's being disowned by his strict Mormon family. We root for him as he rebuilds his life in college, and cheer when he wins a coveted position at the Johnson Space Center in Houston.

But sympathy turns to dismay to disbelief as he acts out his fantasy to break into a high-security lab, make off with rocks from the first Apollo moon landing and trade his priceless cargo for the outrageous sum of ... $100,000!

Since this is a true story, the end is never in doubt, but Mezrich maintains a chord of suspense from the beginning to the ridiculous rendezvous at the climax. This tale of "the most audacious heist in history," built from interviews with an older and wiser Roberts, explains a lot, but the question remains: What was he thinking?