This is yet another Heinlein’s juveniles, and yet another good time.
It’s classic SF at it’s finest; it would have made a great B movie.
You’ve got a courageous, resourceful young man; a plucky girl (literally–
she’s ten years old); a gifted scientist (her father); bug-eyed monsters;
super-science; and a wonderful lessons in how to save the world and deal
with the town bully, respectively. I couldn’t take it at all seriously,
especially the technology, but gosh it was a fun thing to read while home
sick with a cold.