Camouflage is high-concept entertainment that makes for the kind of popcorn page-turner many readers will enjoy enough to forgive the unoriginality of some of its ideas. The story involves two aliens stranded on Earth for so long that neither remembers its origins. Neither one knows about the other, nor has either's existence yet been revealed to humanity.
The changeling hails from a world of such harsh climatic extremes — its wildly elliptical orbit takes it closer to its sun than Mercury and farther from it than Pluto — that its species has developed the ultimate in adaptability. It can survive under any conditions and morph into anything at all, though the process is physically arduous and painful. It also has an insatiable thirst for knowledge. The chameleon, on the other hand, possesses only human form, but can mimic any person in nearly the blink of an eye. Indifferent to knowledge, it is innately sadistic and lives only for its own pleasure, which usually involves killing people in nasty ways. None of this is terribly fresh. The changeling will remind you of the liquid metal guy in Terminator 2 (in one scene it even mimics the floor tiles), and the chameleon is roughly similar to a creature in the lesser known 80's flick The Hidden.
Where Camouflage rises above its swipes is in Joe Haldeman's crisp and witty writing. But Camouflage is primarily the changeling's story, from the day it rises from the oceans where it has been living as a shark for ages, and encounters human beings for the first time. Haldeman manages to give this ever-morphing creature a sense of individuality, even as it is trying on new identities wherever necessary. Tirelessly absorbing information, it learns more and more about humanity, eventually developing a sense of empathy towards other beings. It endures WWII in the role of an American POW in the notorious Bataan Death March. It discovers human sex (in a scene that manages to be both funny and horrific). It obtains doctorates in numerous fields under numerous names, and even becomes a popular professor at one point. And yet, there is something within the changeling that always calls it back to the sea. In its shark guise, it returns there whenever it can.
The chameleon isn't explored nearly as three-dimensionally. It's the Bad Alien. We know nothing of its origins like we do the changeling's, and all we learn about its biology is that it has DNA while the changeling doesn't. Where the changeling's changability is described in the context of its species' evolution, for all we know the chameleon just alters its form by magic. And though we're told it has been living among humans since the stone age, we really don't know why it loves to kill. Okay, so it's a biological imperative, to eliminate competition in the environment, but Haldeman never explains why it hasn't used its evolved intelligence to overcome that imperative. (The changeling kills the first human it sees when it comes out of the ocean, but quickly learns such behavior is unacceptable among the species.) What we do learn of its history is sometimes eye-rollingly arch. It was Josef Mengele's assistant in the concentration camps at one point, fer cripes sake (and, in a nastily cynical turn, later works as a Mossad agent). Lucky thing that it's a shape-shifter; otherwise those horns and the forked tongue would start to make folks suspicious!
The novel's human characters are examining an alien artifact raised from deep beneath the sea. I've often marveled at how aliens in SF just seem to possess this innate knowledge to manufacture utterly indestructible substances that cannot even be minutely scratched by the most powerful tools we apply to them. I mean, here we are, the poor pitiful human race, and all of our Galileos and Copernicuses and Newtons and DaVincis and Einsteins and Feynmans and Hawkings, with all of their staggering intellect put together, have never been able to give us immortality or an indestructible anything. And yet, here are these damn aliens, casually living forever and growing back severed body parts and breathing underwater and building things nobody can break and having better sex than you do as if it were just another day at the office. It just ain't fair, I tells ya!
Anyway, the human characters mostly fill stock SF roles as scientists doing the Analog-ish solve-the-problem thing. The trajectory of the story is fairly obvious. We're waiting for changeling, chameleon, and humans to meet. The stage for this is set on the Samoan islands, where the artifact is under study. Happily, this part of the story, though we know where it's headed, is great fun and has plenty of suspense to hold your attention. I was entirely happy to suspend my nitpicks about all of the plot's little nagging issues at this point and allow myself to get caught up in the flow. The writing is tight, almost Crichtonishly so. You're really rooting for the changeling not to have its cover blown, even if the chameleon remains frustratingly unidimensional and the climactic showdown kinda perfunctory. If Haldeman had given more balanced development to the two beings, rather than giving the lion's share of screen time to just one, I can only imagine how much more dramatic tension he could have built.
I can see Camouflage making a decent movie. While it isn't among Haldeman's more timeless tales, it is a diverting beach novel that delivers a good read. Of course, if you do read it at the beach, you might think twice about going into the water.