Apparently instant oatmeal (maple ginger instant oatmeal, to be precise) is like Yeerk heroin, so the Animorphs decide to run a mission down to the Yeerk pool, and see how many Yeerks they can get addicted to it (a process which eventually drives them mad). Man, just typing it out like that makes me feel like their whole plan was super fucked up, and the fact that no one really put up more than a token resistance to it is NOT a good sign for both the morale and morality of our heroes.
Aside from the oatmeal complication, this is actually a pretty straightforward "break into the Yeerk Pool and cause some havoc" story (which we've had several examples of by now). They use mole morphs to dig a tunnel into the Yeerk pool, after new tech at the normal entrances means they have to find another way in. It takes them a week to dig the tunnel, at which point they head down it. This brings them to a bat cave, where they switch morphs and enter the Yeerk pool. Chaos ensues.
There really isn't much under the surface here. There are two main thematic threads here, and none of them are hit upon all that hard. This is Rachel's book, and we do get a little insight into her psyche, that even when she seems gung-ho during missions, and is always the person who says "let's do it", she isn't always truly enthusiastic. The warrior persona is a role she lives with now, and she feels pressure to maintain it, even while dealing with the same fears and traumas the others are.
The other thing is something I already mentioned above, and that's the slippery slope our heroes have most definitely started on. When does an action in war stop being justifiable? How do you balance actions necessary to defeating your enemy, without descending to their level? (Assuming of course that your enemy is at fault, or to blame.) Drugging a thousand Yeerks with oatmeal, condemning their hosts to lives never free of the Yeerk in their heads, most likely spent institutionalized due to the outbursts from the mad Yeerk that can't be controlled. Even Cassie can't say for sure whether what they're doing is right or wrong.
A little thing that bothered me: Rachel saves a man from committing suicide at the beginning of the book, and then she makes some terrible comments about people who commit suicide that at best portray a stunningly immature understand of why people kill themselves, and at worst betrays the author's own feelings regarding the subject. I know this book was written over twenty years ago now, and we definitely weren't having discussions in the open about mental illness and depression like we do now (though we still have a LONG way to go), but Rachel's attitude is never called out, and the other characters make some callous jokes about insanity as well, so the overall impression is that Applegate just didn't think those comments were a big deal. (This is especially surprising since she's normally a sensitive writer who gives great consideration to tough topics.)
Overall, this one didn't work for me that well. The silly premise was not quite overcome, and the books that are just straight up action are never going to be my favorite.
Next up: Ax, mosquitoes, and the mysterious z-space!
[3.5 stars]