Dr Leonard Pallister was a scientist who went to a scientific conference in 2010. He was a shoo-in for the Chesterton Award, but lost to Owen Stanford's team. When they disappeared at the conference (actually they had slept in and went to have breakfast elsewhere), Theo Lawson believed that Leonard had killed them in revenge.
At the same time, a demonstration with vodium started producing wormholes. One of these wormholes pulled in his shoes, forcing him to walk in his sock feet. People were also pulled in, leading to rumours of disappearances. When one scientist disappeared during a lecture Leonard was watching, Leonard saw it and decided he had to try to leave, which is when Theo accused him. At this point, the Eighth Doctor explained what was really happening. Leonard helped find Wanda Rothman, who was researching the vodium. He also helped Asha Qureshi and Rafshaw to find and neutralise a sample, but they were too slow and Leonard was pulled into a wormhole, presumably killing him. (AUDIO: Situation Vacant)