Masters of the Universe • She-Ra, Princess of Power • The Secret of the Sword, Part I - The Sword of She-Ra {Read Along Book • Kid Stuff Records & Tapes DBC #297}

The 1985 Masters of the Universe children's books, The Secret of the Sword: The Sword of She-Ra (Part I) & The Secret of the Sword: The Princess of Power (Part II), adapt the 1985 Filmation film, The Secret of the Sword. 

Prince Adam journeys to Etheria to find his long-lost twin sister.
Edited Description Taken From An A*z*n Review:  
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. 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 (although one has to put from one's mind the fact that they quit making He-Man episodes for the purpose of making She-Ra ones instead).
All the art in these books is taken directly from the film & 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.