Professor Green quit 'Celebs in Solitary' just hours before the experiment was due to finish.
The 34-year-old rapper had seemed to adjust well to life in his Belfast cell on the Channel 5 reality show - which sees stars put in solitary confinement for an experiment - but decided to leave during Wednesday's episode (12.09.18).
Pro - who was joined by Anthea Turner, Shazia Mirza and Eddie Hall on the intense programme - hit the red button to signal to producers his desire to leave the cell after the episode was focused on punishing the celebrities.
Although he said he felt "really good" about his decision to quit, he did making an emotional phone call to his nan afterwards to tell her he was safe and coped well enough in his surroundings.
Over the first three days the stars got used to their new environment, Pro - whose real name is Stephen Manderson - kept himself busy writing lyrics non-stop.
He also had time for self-reflection, and had some existential questions as he stayed in isolation.
He pondered: "Is it weird that I'm thinking more about what's going on in the other cabins than what I'm thinking about in the world I'd normally exist in?"
Pro knew he was close to the end when he left, which led to some suggesting the show could be a fix.
But presenter George Lamb explained the celebrities had kept track of their food and knew when they were eating their "last supper".
'Celebs in Solitary' - which is airing on the three nights between Celebrity Big Brother's conclusion (10.09.18) and the new 'Big Brother' series on Friday (14.09.18) - concludes on Thursday September (13.09.18) at 9pm on Channel 5.
One more star will quit before the experiment concludes.