Set on a bad 21st century rip-off of Star Trek, the young ensigns aboard the starship Intrepid discover that their ship has an astonishing turnover of junior officers. They soon set out to investigate why so many of their shipmates are destined to die, while the senior officers (and one dashing young lieutenant) survive unscathed. The answer leads to a breaching of the fourth wall and a quest that draws its cues from a certain Star Trek cliche that I won't reveal here.
There were two ways John Scalzi's Redshirts could have gone: 1) it could have been a brilliant and clever deconstruction of the plot contrivances of Star Trek; 2) it could have been a one-note satire, too smug and self-satisfied for its own good. Unfortunately, Redshirts takes path #2.
I really wanted to like the novel (and three codas) -- in the hands of a stronger writer, this idea could have become a multilayered satire, but Scalzi is unfortunately not up to the task. Instead, the Star Trek jokes are obvious, and the pseudo-Trek universe of the Intrepid is significantly less inspired than the film Galaxy Quest, to which the novel has more than a passing similarity. Unlike Galaxy Quest, which was a loving send-up of Star Trek (and indeed is more entertaining than the Next Generation films), Redshirts seems at times to have a smug contempt for the source material. It focuses on the bad science and plot problems of Trek, rather than the sociopolitical commentary and iconic characters that made Trek great.
In many ways, Redshirts feels like something Scalzi wrote for fun and never intended to publish. It lacks the creative heft of much of his other work and is probably not worth purchasing at full price. It's not terrible, but it's not worth the brief amount of time it takes to read it.