Our heroine is a musician; she's taken on the life-task of performing a difficult piece of music. It's difficult, we learn, because its composer meant it as a joke. But enough musicologists back in the day hadn't got the joke, they'd taken this piece seriously. Engineers had designed a musical instrument capable of playing the work; musicians set out to perform it. Our heroine had a couple of extra arms grafted on so that she might be capable of it. So is the composition still a joke? Or has it become something else just because people treated it seriously?
A civilization joins the galactic community partly thanks to a mysterious holy book which appeared to them early on—which guided them towards what they needed and tells them that another spacefaring civilization is pretty amazing. Everybody kind of suspects that the book was planted thousands of years ago by that other civilization, but it's not clear what to do about it. How to untangle the hoaxy bits from the truth?
There is a problem with supercomputers running true-to-life simulations. They help you predict the future, to anticipate how people will react. But if you start a simulation, create all of these simulated beings— What's your responsibility to them? When you've found what you want from the simulation, can you just snuff out all those lives you've created? Sure, they're not real. Except they're pretty darned real as far as they know.
Right, so all of that and rollicking space opera intrigue. Good stuff.