"Happy Ending" is a 1948 science fiction short story by American writer Henry Kuttner.
As the story begins, a man named James Kelvin presses a button and returns to a lab with a moustached scientist who informs him that he is now a millionaire.
Every time he presses the button, he will temporarily enter the mind of someone in the future and can read that person's thoughts and gain his abilities.
He begins a scientific conversation with him on proteins and amino acids, with ideas stolen from the mind of the future scientist, Quarra Vee.
Moments later, Tharn appears and, when Kelvin presses the button, he gains the ability for a lethal mental attack.
The scientist Quarra Vee, and his android companion, Tharn, are preparing to go into the past to recapture a dangerous runaway robot.
As he enters, a rope knocks aside the glasses which are supposed to protect him from attempts to tamper with his memory.