No one but LOUIS WU! Wu is 200 years old and looks like he’s in his 30s.
A chain reaction of millions of tightly condensed stars in the Core of the galaxy has exploded and is sending out a massive wave of radiation that will eventually wipe out all of the life in the Known Universe!
“Oh. Well, nevermind then.”
The Puppeteers take this threat very seriously and start investigating ways to move their millions of year-old society to someplace safe in the dwarf galaxy above the Spiral. However, this is a problem because they’re all (mostly) immortal and really-really hate risking their lives and making the kind of efforts to save themselves will require a lot of incredibly risky stuff. So they need a race that is incredibly cavalier about their lives, tool-using, but objectively kind of stupid. Yes, HUMANS!
Humanity has been in space awhile at this point and compared to the Puppeteers, they’re ignorant savages. So much so that their faster than light travel is almost 400 times slower and won’t be able to move anyone when the disaster happens. Which no one is worrying about because 20,000 years.
No one but LOUIS WU! Who is 200 years old and looks like he’s in his 30s. He’s one of the world’s richest and most famous men and brilliant scientists but as one of the oldest people alive (he’s a first-generation immortal), he also is having serious issues adjusting to immortality and jumps at the deal the Puppeteers offer as he thinks that getting their hyperdrive NOW will allow humans to work on it for 20,000 years and thus actually be ready when their stupid narcissism catches up with them.
The first problem is that Louis Wu doesn’t get to pick the crew he’s heading and he’s also objectively a jerk. I think Larry Niven thinks he’s a jerk too but he doesn’t think he’s nearly as big an asshole as he actually is. If you get what I mean. In simple terms, he’s a condescending sexist who constantly thinks of his companion, 20-year-old Teela as an ignorant child but that doesn’t stop him from sleeping with her. Teela, herself, is the magic pixie dream girl who doesn’t know space is dangerous but is the luckiest unlucky woman in the galaxy due to selective breeding.
“You can’t breed for luck!”
“You bred for psychic powers!”
The second problem Louis Wu has is that the Puppeteers are hedging their bets on humanity and have also included Kzin among the crew. Kzin are the other stupid tool using space-capable race cavalier about their lives and humanity’s mortal enemies: A stooping race of hostile tigers called the Kzin.
Except…not really our mortal enemies anymore. Larry Niven sets the book after humanity has utterly spanked the Kzin in five previous interstellar wars that wiped out 2/3rds of the Kzin males each time because they threw themselves at humanity with suicidal wave tactics that don’t work in space. So much devastation happened to the Kzin that the Puppeteers suggest that went through an evolutionary leap because the ones smart enough not to be suicidally bloodthirsty were the only ones to breed for a couple of centuries.
(But they’re still jerks)
The Kzin are odd in that only the males of their race are sentient and the females are NOT, which the females of the books find evil and wrong! Some fans speculate the men devolved them because its a creepy concept either way but creepier that way. Notably, Larry Niven made them part of Star Trek when he wrote a episode of the Animated Series.
And they end up finding THE RING which is a dyson sphere-sized ring habitat that can travel through hyperspace and thus transport trillions!
And who will get it!
A classic book of science fiction that also has dated badly in some respects.