I was in 6th grade when I purchased this in paperback at a little bookstore in York Beach, Maine. It made such an impression on me that I named one of my guinea pigs Varina. Now, rereading it as an adult in my late 40s, I'm pleasantly surprised that I like it as much as I did then.
The reader is dropped into a time when Earth is controlled by the Delikon. It isn't clear what humanity did to earn its galactic overlords, only that it somehow involved ambitions in space.
Varina has served nine terms on Earth as a teacher molding generations of young human proteges to be governors. Even though she is 307 Earth years old, looks like a human child, and is considered a child on her home planet D'Laak, the time has come for her to return where she will live a life of luxury for her service. But she doesn't want to leave.
During a final expedition with Jason and Alta, two of her last students who are ready to go off to academy, they and their escort Cornelius are captured by human rebels who are determined to overthrow the Delikon. Varina finds that Aron, one of her former students, is now a governor leading the rebellion to attack Kelidor, the seat of Delikon power.
Although Aron is happy to see Varina, she is reserved and slightly repulsed at the effect aging has had on him. Traditionally, the Delikon never see their students again, so Varina is amazed to see the older man Aron has become. Aron informs her that he is leading the rebellion because it's time for humans to rule themselves again.
Meanwhile, Sidra, the Delikon leader on Earth and both mother figure and commander to Varina, receives orders that her people are to leave Earth for good. Humans are a failed experiment that will never evolve to anything useful by Delikon standards. And besides, it's very expensive to maintain the Earth colony.
Varina, Jason, Alta, and Cornelius escape from Aron and make a treacherous journey back to Kelidor. Along the way, they encounter battle between humans and drones, the killing machine warrior creatures used by the Delikon as an army.
Throughout the story, Varina is torn between staying on Earth and returning to her homeworld. She's lived on Earth so long, that she seems to have developed some human traits.
The theme of belonging to two worlds and having to choose is agonizing. And as the story progresses, the clock is ticking as the Delikon restructure their bodies back to their alien form and prepare to leave Earth behind.
I won't give away anymore of the story here, but hopefully this gives a good setup.
I feel like this book has held up remarkably since it was published in 1977. I could see it as a series on Netflix. It would be a great world to expand. Sadly, I think it will fade into obscurity as it never seemed to catch on when it was in print. Most of H.M. Hoover's books seem to be out of print, and I have never seen her on recommended YA booklists or heard of her other work. I purchased this copy on Amazon as a used middle school library book taken out of circulation. It's staying in my permanent collection because as far as books go, it feels like a reunion with a long lost friend.
I highly recommend that you read it if you have a chance or if you're interest is piqued. It's good science fiction and a sadly overlooked gem.