This is the final series in the Chocky trilogy; not really bad but imho not quite living up to its predecessors.
It is in some ways a rerun of "Chocky's Children" but this time with an obnoxious military man replacing the businessmen of the previous series. But for me it's nowhere near as good. I don't especially like army brasshats myself, but why did this one have to be quite such a caricature? He put me in mind of the evil professor in City Beneath the Sea.
This series also suffers from the lack of a central character. Matthew Gore, now visibly adolescent rather than the young kid of the first two series', appears only at the beginning and end, while Albertine, now up at Cambridge, never quite manages to take his place. At best she is only a kind of "first among equals", and frequently not even that.
There is also a distinct inconsistency from the previous series'. "Chocky's Children", now gathered together from all over the world (would Chocky have approved of that?) have set out in pursuit of the secret of Cosmic Energy, precisely what Chocky had cautioned Matthew not to do. Indeed Matthew is apparently still following her original advice, continuing his career as as artist and avoiding anything of economic or military importance. If he is right, then logically the others are wrong, but there is little suggestion of this.
In the end, of course Chocky, aided by Matthew and another of her own species, manages to save the day. Apparently they are all to live happily ever after; but I wonder if that would really be possible, given the amount of attention they have by now drawn to themselves. I fear the cat is well and truly out of the bag.
Still, it's not too bad as kids sf goes. You may be less finicky than I am. Use your own judgement.