A couple of decades ago, I read my sister's copy of Man of Many Minds, and greatly enjoyed it: enough so that I hunted out a copy for myself. It tells the story of George Hanlon, a young man who can read minds, who becomes a Secret Agent. It's very much of its time, and the cultural assumptions grate a little (for example, I believe there are two women in the whole book: his mother who dies nobly before the tale starts, and a secretary who is scared by a pigeon using her typewriter), but the story of how he discovers that he can control animals' minds, his work with the fascinating plant people, and the descriptions of dispersing his mind in birds and insects, gave it some good SFnal depth.
I reread Man of Many Minds recently, and although it doesn't stand up to my earlier enthusiasm, it is still mildly interesting and fun. So when I discovered that there was a sequel (the Web is making this sort of discovery trivial nowadays), I decided to get a copy of that, too.
In this, George Hanlon, mind-reading Secret Agent, is sent on a mission to an alien world where the inhabitants seem ready to join the Interstellar Federation as full members, but where there seems to be a peculiar opposition growing up. He ingratiates himself with the local crime boss by posing as an animal trainer, and gradually discovers the source of the opposition.
Unfortunately, this is rather inferior to the first book. The cultural assumption grate even more (for example, there are absolutely no women in the book at all!), possibly because the rest of the story does not counterbalance that flaw this time around. The alien people are not as fascinating as the plant race: we are told that their mental processes are very different, but they all seem perfectly human, and homogeneous. (And just how do their pentagonal rooms fit into their buildings?) The animal training, after a detailed buildup, is simply dropped as soon as it becomes of no more use. The other alien causing all the problems is very underused. And Hanlon's increasing powers are going off in a less interesting direction: physiology rather than psychology. Ah well.