This title is rather hard to find in hardcover.

A sequel to the novelet "Clash By Night" from Astounding March 1943 - this was serialized in Astounding May to July 1947 (as by "Laurence O'Donnell" - one of Kuttner's most common pseudonyms, often in collaboration with C. L. Moore.) The hardcover came out in 1950. The 1958 American paperback edtion was re-titled Destination Infinity.

[from the back cover of a pb edition]: THE IMMORTALS lived a thousand years or more, blessed by the poisonous magic that had destroyed Earth. They ruled the keeps of Venus, those last cities of the race of man that were huddled beneath the shield of planetary ocean. Avoiding the harsh realities of surface life, the Immortals seemed content to watch the race drift toward inevitable death - until one of their own was born in hatred and bred in violence - a violence that made him explode in a rebellion that would take the race back to the stars!

[from the inside blurb (of another edition)]: Sam Harker was born into a world that he must smash before it could smash him. He never knew his parents - never knew that they were Immortals, members of the ruling class that could reach a thousand years or more. Sam Harker's mother was cheated of her immortality, dying as she brought him to life, and leaving his father so filled with hatred for the killing infant that he would damn the child into an eternity of mocking hell. Sam Harker was a lifelong prisoner of hatred - and the only man who could save his world!