Carmen Dula and her family are relocating to Mars for half a dozen years. They've won the lottery and it's a huge, historical honor--as there are only 100 people living on the new colony. But it's a long ride there and the sixteen-year-old has a fling with the pilot which doesn't remain a secret for long. Once they get to the colony she's singled out by the woman in charge, who simply doesn't like her and keeps on putting her on detention for misbehavior. In one of these instances she's forbidden to leave the compound so what does she do? She gets in a spacesuit and goes out to explore by herself. She falls into an underground cave system and is rescued by a crab-like alien and taken to his colony. They repair her broken leg and send her back home. What do they want?
We learn that they've been on Mars for thousands of years and have been studying Earth and know our history since we've had radio waves. They aren't native Martians at all. They've also brought a fungus with them that is potentially fatal to humans. Though they cure the infected in the colony it makes the rest of the Earth leery to be in contact with them--and the Martian base is isolated. The last third of the book skips entire years--and we learn that these "Martians" are actually biological creations of a very slow-moving, extremely long-lived species, specifically created to study humans and prepare them for their arrival....
While I did enjoy this book, it kept on reminding me of John Varley's much superior Mars trilogy, without the charm. This is the least impressive book by Haldeman I've read, but then again how can it compare to THE FOREVER WAR and FOREVER PEACE?