So this book was my first to read out of that whole collection from my brother. I had read one other Hal Clement book, "Mission Of Gravity" but that was at least 25 years ago. This one, I believe, was Mr, Clement's first published work, written in 1949. Unfortunately it shows. The book opened delightfully, with the nice hard science that the author is known for. A protoplasmic alien creature has crash landed on earth while chasing another of the same species who has committed some sort of crime. The "hunter" alien absorbs into a 15 year old boy and uses him to function and chase after the criminal alien. Yeah I know it sounds a bit hokey but the first 1/3rd of the book was quite riveting to see how the biology of the alien species worked. This was just the sort of hard science I was looking for. Unfortunately, the actual "story" took off from there and turned into a detective story that seemed aimed at younger readers, reminiscent of Heinlein's juveniles only not nearly as good.
The book spawned a sequel several years later, which I may read, but I may have to get through those other 99 books from my brother first.