Another book down on the reread-Heinlein project. (Leaving 21 to go.) This one is in his juvenile series from the 1950s. My recollection is that I read it once in my youth (sometime in the early 1960s). I bought the Ballentine/Del Rey paperback at some point in the late 1970s, can't remember if I actually reread it then, though. But (yay!) I got 'er done this time.
Teenager John Thomas Stuart IX comes from a long line of explorers and risk-takers. While on an early interstellar expedition, his great-granddad picked up a cute creature on a remote planet, brought him back to Earth, named him "Lummox". Unfortunately, that expedition was so early, they were not sure what star system they were exploring at the time, so Lummox's home planet remained unknown.
But years later, Lummox has grown to the size of a Triceratops, and is even more heavily armored. One day, bored, he goes exploring, accidentally wreaking property damage and consternation upon John's neighbors. Demands grow for Lummox's destruction.
But in the meantime, a new race has made itself known to humanity. They are demanding the return of a Very Important Entity, stolen from their planet years back. And they are threatening planetary destruction unless their Entity is returned.
It would be surprising if that were a coincidence, and it's not.
You might expect an explicitly "juvenile" book would concentrate on young John Stuart and his efforts to keep Lummox safe. But much of the book is devoted to Mr. Kiku, a career bureaucrat (today we'd call him a member of the "deep state") devoted to managing peaceful relations with a host of alien races. He takes on the thorny task of preserving Lummox from Terran xenophobes, and also avoiding that whole Earth-destruction thing. This involves very little action, but lots of talk, dealing with idiocy, bypassing ignorant superiors, and political maneuvering.
Don't get me wrong: I found that stuff good, and interesting, and actually hilarious in parts. (Heinlein had a good ear for that sort of thing.) But I'm kind of surprised that juveniles of the day would sit still for it.
I guess they did, though. I did.