Skak was a grey, spindly stone-like alien from the Bedra Elite.
Ephnol contacted Skak to help him. Skak tried to set Skak free, which caused the house of the O'Brians and a Victorian house to swap places in time. Deathy caught Ephnol together with Sarah Jane Smith and her team and put the houses into the right time again. Deathy took Skak and Ephnol with him to bring them to trial. (AUDIO: The Ghost House)