77. Hamilton, Peter F. Judas Unchained
Imagine a universe in which populated worlds are linked by railway.
OK, try again with the important detail that the actual connections are wormhole "tunnels", seems a little more plausible now doesn't it?
This is a universe without manned spaceflight (wormholes reached Mars at the same time that the last NASA mission did), but with mass colonisation of the stars facilitated by unmanned probes.
It's also a universe with known aliens (who generally keep out of the way of humans), and one secretive one. Well, at least if you believe the universe's Number One Wanted Criminal who is a terrorist working against a conspiracy only he can see in the government planted by that secretive alien (that noöne else thinks exists).
Add the discovery that an unusual astronomic event that's just visible to human telescopes turns out to be instantaneous and all of a sudden mankind wants manned spaceflight; and that really opens Pandora's Box….
Whilst this is published as a pair of books, the story flow is more like a quartet (in a very similar way to Donaldson's Mordant's Need), with sections that might be described as Exposition, Beginning, Middle, End. It's a format that works very well in this kind of stand-alone setting; and Hamilton's talents are well suited to this kind of length, particularly as he managed to avoid the temptation of a literally Deus ex Machina ending that he succumbed to in the Night's Dawn trilogy.
Possibly the best new Science Fiction of recent years; and hard to put down.