Rogue time traveller (Guardian At The Gate)

One Welsh institute once had to "deal with a rogue time traveller who had created a machine which opened up unstable rifts". This led to their creation of a device which could allow humans to safely pass through unstable rifts. (AUDIO: Guardian At The Gate)

Behind the scenes
The "institute in Wales" is implicitly Torchwood Three, but this could not be mentioned explicitly for copyright reasons.