The Sirens of Titan is one of the masterpieces of Kurt Vonnegut, his first classic although only second novel, which would already immortalize him as one of the most significant Authors of the 20th century, along with the better known Slaughterhouse Five and Cat's cradle. There, a chief trait of the Author, who now fully found his style, works at its best: the story appears to be a random fantasy, with grotesque elements apparently made up at the same time that they were being written, going along with a linear plot more or less following a thread, but that is replete with irrelevant, absurd bits, all seemingly going nowhere and distracting from the main story line, itself also looking nonsensical.
It is only at the end that everything unties, and deep meaning is given to even the most trifle details, which have been made grotesque to imprint a mark in your memory, and come back later at the time of the big revelations. That not only turns the main plot from an entertaining story to a parable of existence, it also shows that nothing is irrelevant, nothing is meaningless. This brings, to literature, an almost religious experience: finding meaning in one's seemingly absurd and empty personal story. Everything is there for a reason—not even a reason—for a purpose.
An illustration of this Nobel-prize winning breakthrough in literature, is Salo, the duck-looking alien who makes embarrassing noises as he walks.
The Sirens of Titan is as Sci-Fi as you can make it. You could rightly say it is too-much Sci-Fi, it is pushing the style too far, which earned Vonnegut the reputation of being a "humorous" writer. There is nothing comedic about it. Vonnegut can indeed make you laugh out loud. But not with jokes. He can make you laugh with the same knob in your soul that brings you to cry, to fear and to despair, and that can be tuned to laugh, to understand and to accept. People focused on the laughers, because that is the most primitive and most easily captured feeling. But are you laughing now:
"Well," said Rumfoord up in his treetop, "if you feel we are doing you some sort of injustice here, suppose you tell us something really good you've done at some point in your life, and let us decide whether that piece of goodness might excuse you from this thing we have planned for you."
"Goodness?" said Constant.
"Yes," said Rumfoord expansively. "Tell me one good thing you ever did in your life — what you can remember of it."
[...]
And then he remembered Stony Stevenson — his friend. He had had a friend, which was certainly a good thing. "I had a friend," said Malachi Constant into the microphone.
"What was his name?" said Rumfoord.
"Stony Stevenson," said Constant.
"Just one friend?" said Rumfoord up in his treetop. "Just one," said Constant. His poor soul was flooded with pleasure as he realized that one friend was all that a man needed in order to be well-supplied with friendship.
"So your claim of goodness would stand or fall, really," said Rumfoord up in his treetop, "depending on how good a friend you really were of this Stony Stevenson."
"Yes," said Constant.
"Do you recall an execution on Mars, Mr. Constant," said Rumfoord up in his treetop, "wherein you were the executioner? You strangled a man at the' stake before three regiments of the Army of Mars.
"This was one memory that Constant had done his best to eradicate. He had been successful to a large extent — and the rummaging he did through his mind now was sincere. He couldn't be sure that the execution had taken place. "I — I think I remember," said Constant.
"Well — that man you strangled was your great and good friend Stony Stevenson," said Winston Niles Rumfoord.
Malachi Constant wept as he climbed the gilded ladder.