The first concerns an expedition to some alien construct. Dubbed "Blood Spire" by the rich eccentric leading the rest, it's a towering puzzle box floating just off the surface that sprays out the pieces of those who can't keep up with it's mind-warping math problems. Remember that bit in the film Contact where they had to think in entirely different dimensions to make any sense of the wormhole schematics? Yeah, it's like that but more obtuse.
Narrated by the rich eccentric's friend, things take a fairly standard course of delving deeper into the alien labyrinth, finding ever more difficult problems, and experiencing ever more creatively horrible dismemberments. Narrator and Rich Guy resort to drastic physical augmentation to not only survive but to think faster, to react quicker, to fit through the ever narrowing hallways of Blood Spire until they literally resemble diamond dogs.
And to what ultimate purpose? What cyclopean secrets does Blood Spire hold? Hell if I know, 'cause that's not what this is really about. It's about the very human desire to explore and learn taken to obsessive extreme. How much would you sacrifice to learn the capital "T" Truth of things? How much would you mortify your own flesh to get at a secret so strongly kept? Diamond Dogs is Reynolds asking these questions, writing beyond the usual limits of his genre to touch on deeply personal and human themes.
Turquoise Days, in contrast, comes across as weaker. Set on a planet of endless oceans and continent-sized intelligent algae, it follows a young woman who finds herself caught up in a whole mess of political intrigues and outright invasion when all she really wants to do is study sea life. One sea life in particular - the alien algae that ate her sister.
Well, not "ate" really. The pattern-jugglers - which you Revelation Space fans will remember - have a curious habit of absorbing certain humans that prove overly receptive to their "communion" practice of interlocking consciousnesses. Big Sis was just such a human, leading Little Sis to fear she will come to the same fate... and secretly longing to. Since people absorbed by the pattern-jugglers don't exactly stay gone, their neural pathways preserved inside those massive islands of algae.
"We shall swim out to that brooding reef in the sea and dive down through black abysses... and in that lair of the Deep Ones we shall dwell amidst wonder and glory for ever." ~ H.P. Lovecraft
It's actually quite touching and it's what links this with the much more overt and visceral Diamond Dogs. Reynolds, despite writing the hardest of hard sci-fi, never neglects the human core of his stories. On the contrary, these very familiar desires for love and understanding are all too human, all too applicable to our daily lives trapped on this boring blue rock. That's what makes Reynolds one of the best in the game today, despite his stiff prose.