The 1985 Masters of the Universe children’s books The Secret of the Sword: The Sword of She-Ra and The Secret of the Sword: The Princess of Power adapt the 1985 Filmation film The Secret of the Sword. Here, Prince Adam journeys to Etheria to find his long-lost twin sister.
These two books comprise an exceedingly faithful, if abridged, adaptation of the film, and any evaluation of the story in the books holds equally true for the film. I personally think it’s pretty good; sure, it wanders around some, but it has a lot of characters to introduce us to, which it does a pretty good job of, and it contributes to the He-Man mythos in meaningful ways, both by introducing Adora/She-Ra and incorporating Hordak and the Horde into the Filmation world.
All the art in these books is taken directly from the film. And given that the read-along audio was taken from the original movie soundtrack, this was the next best thing to watching the movie in the days before it was available on home video.
These sorts of film adaptations are largely unnecessary merchandise tie-ins, of course, but that doesn’t mean they aren’t fun.