This was Larry Niven's first novel, published when he was about 28, and in a way it's rather sad to say that it remains for me the most thoroughly satisfactory of all his many books. The scenario is good and well explained in detail; the story is satisfying; and there's a good variety of characters (characterization tended to be weaker in his later books).
The background is that, two billion years ago, the galaxy was dominated by the thrintun, a race of only moderate intelligence that was able to make slaves of all other intelligent beings by telepathic control.
The thrintun and most of their slave races suddenly became extinct two billion years ago (he explains why and how); but a single thrint has been preserved all that time in a stasis field on Earth, and is rashly woken by scientists. He immediately sets out to retrieve his amplifier helmet, saved elsewhere in another stasis field, which will enable him to control a whole planet instead of merely a few dozen people at a time.
To complicate matters, a man has received a copy of the thrint's memories, and is also searching for the amplifier helmet for his own benefit.
It's characteristic of Niven that his thrint, an ugly alien monster with the personality of an arrogant slob, nevertheless seems as human underneath as any of the other characters, and we even feel a certain sympathy with him at times.
You're perhaps wondering about the title. A ptavv was one of the rare thrints who lacked the telepathic power that distinguished them from lesser beings. As all humans lack this power, Earth seems rather like a world of ptavvs to the last thrint left alive.
Uncharacteristically, Niven never explained how one thrint could possibly control a planetful of intelligent creatures, even with an amplifier helmet. Simple telepathic power isn't enough: the thrint would need a brain the size of a planet to handle the multitasking. Perhaps he could do it by issuing the same blanket command to everyone: “LOVE ME.” But, in the book, the idea of the whole human race becoming slaves to a single thrint remains a vague background threat without any added detail.
Trivial note: a minor character in this book is called Herkimer, which was also the name of an android in Clifford Simak's novel Time and again (1951).
Written in March 2007