Jonah Bevan

Jonah Bevan was 'taken' by the Cardiff rift around 2008, when he was 15 years old. The rift took him to a "Burning Planet" in a solar system about to be destroyed. He was rescued, but was was stuck for 40 years before he was returned by the rift to Earth. During that time he had stared into the heart of a Dark Star and what he had seen had driven him mad, resulting in him screaming continuously for a period of 20 hours each day.

On Earth he had been missing for 7 months when Gwen started to investigate after seeing footage of Jack Harkness travelling to the place Jonah disappeared.

Eventually with Ianto Jones's help Gwen found Jonah on a Torchwood facility on Flat Holm, 40 years older and deformed by the heat. She told Jonah's mother, Nikki Bevan, and took her to him. Nikki thought it was a sick joke until Jonah started saying things only he would know. Nikki hugged him but was told they should leave by a staff member. A few seconds later Jonah started screaming, which made Gwen and Nikki back away. His mother agreed to come visit him again, but wished that she had never learned his fate. (TW: Adrift)

Behind the scenes
There is belief among fans that the burning planet that Jonah was saved from was Gallifrey, the man who pulled him from the flames was in fact, the Doctor, and the destruction of the entire solar system was part of the Last Great Time War. As it was shown that Dalek Caan was able to break the time lock, it seems probable that the Rift is able to bypass it also. However, there is no evidence to support this theory.