I really enjoyed reading this book. I was a kind of a space geek as a kid. (Still am.) I wanted to be an astronaut. (Still do, although the chances of that are about 1 Å slim.) I devoured anything about the space program I could in Life, National Geographic, etc. In 1957, like Alan Shepard and his daughter (page 50), I watched with my dad as a bright Russian satellite flew over the Oakland, Iowa football field.
So Stephen Walker goes back and revisits those days of the early US/USSR space race. He reveals a lot of stuff we didn't know back then, mostly due to Russian secrecy, but some due to NASA's happy-face public relations. Much of the Russian-side stuff only became known after the USSR's breakup, and was released without fanfare. Walker culminates his story with a detailed account of Gagarin's one-orbit flight in April 1961, with a brief epilogue describing the fate of the book's principal characters.
Random things I learned:
You did not want to be a Russian dog sent on a space mission. Poor Laika, sent up on Sputnik 2, died of either overheating or asphyxiation. Self-destruct systems on the test Vostok flights blew up some pups. (The self-destructs were to ensure that Vostoks accidentally landing outside the USSR couldn't be grabbed by the capitalists.)
American chimps had it better, but still: Ham's suborbital flight veered off its expected path thanks to its booster running too hot. The cabin lost pressure, the capsule overshot the planned landing zone by 130 miles, and almost sank before ships came to rescue.
Gagarin's flight had its share of peril too. His orbit was higher than planned, which would spell doom for him if his braking rocket failed. His capsule didn't separate from its service module as planned.
In order to secure "official" world records for Gagarin's flight, the Soviets had to claim that he rode his capsule all the way to its landing. That was a lie; Vostoks were designed to eject their cosmonauts and they would parachute to earth separately.
The US manned spaceflight program was on life support in the early 60's. JFK's science advisor, Jerome Wiesner, more or less opposed it, and JFK himself seemed uninterested. But Gagarin's flight (and the disastrous Bay of Pigs invasion) spurred his administration to "do something" to get in front of the Russkies. So after Alan Shepard's flight, JFK made his famous "before this decade is out" speech, and … well, you know what happened.
And a bunch more stuff, but I've typed enough. Walker is a fine storyteller.