The first section of the novel is a kind of prequel—to the book and to the human race. Aliens turned man-apes to people via psychic slabs. That's the initial situation; godlike extraterrestrials are out there. Watch out people.
Rising Action (Conflict, Complication)
Take It To the Moon, Floyd
People discover an alien obelisk on the moon. It sends out a signal to other aliens on Saturn. What should the human race do? Answer: more space ships! (More space ships are always a good answer if you're writing science-fiction.)
Climax (Crisis, Turning Point)
Need Excitement? Get a Computer
The Discovery sets off for Saturn; Hal hijacks the mission and kills everyone but Bowman. Thanks a lot, Hal.
Nothing to Do Now But Explore the Galaxy
Bowman continues on to Saturn alone, and from there through the alien Star Gate and out to the far end of the cosmos. There's not much plot action, but lots of pretty galaxies and suns.
The World Is Yours, Space Baby
The aliens turn Bowman into a super-space baby who controls the earth. As resolutions go, it is unexpected, to say the least.