Operation Time Search has some plot and logic holes big enough to drive a semi through, but I really adored it as a teenager, reading and rereading bits of it. I've seen other people comment that it's a weak book for Norton, but... Well, I can't actually judge with any accuracy and couldn't even if I reread it. Either I'd still love it, warts and all, or I'd dislike it that much more for having loved it once upon a time.

As I recall, there's an SF frame story, and then everything inside is headed much more in the direction of magic (though still science because psychic powers). Atlantis and Mu and time travel and interdimensional beings and mind control and... Also, the ending bit of the frame story makes my head hurt because a time traveler altering things thousands of years ago does not, in any universe I consider logical, lead to abrupt changes in the time he came from, changes that everybody notices and that don't change the history they remember in the slightest.

So, an F from me on that one.