A year ago, Brian Fosters mother and sister Debbie vanished while the family were out picnicking. Brian's father seems disinclined to be too worried or to report them missing, but Brian himself is desperate to find out what happened to them.
This is the start of a book that takes us on a great ride through a future (not that far in the future now, perhaps) where the air is so toxic that cylinders of oxygen are placed around Brian's school in case people exert themselves. The seas are foul, food is completely processed and in poor supply and the land is poisoned, but more importantly to Brian, people are going missing. Together with a mysterious girl who is transferred to his class, whose parents have also gone missing, they try to figure out what is happening.
This is a thoroughly enjoyable story, I actually first encountered it as an adult, but it is a good enough classic science fiction theme that reading a kid's book was no hardship, and I re-read it again often now.
When I say 'kid's book' I mean that it was intended for children at the time of publishing. The two protagonists are teenagers, and act like them except that the obligatory romance and angst that are included these days in YA books are thankfully absent. Brian and Heather do form a relationship, but it is not a factor of the plot.
The only way in which I feel this does come across as a 'young' book is that the conclusion is somewhat simplistic and the bad guys a trifle stereotypical. Other than that, I find it a very thoughtful novel in that it was published in the 70's yet could clearly see environmental consequences. I think it is a great story, and if it has dated quite a bit in some ways (no mobile phones - Imagine!) in other ways it has weathered the decades really well.
I would recommend it to lovers of classic science fiction.