Set sometime on future Earth during a new ice age, scientists discover a Martian warrior in a glacier. The "ioniser" used by the scientists end up causing an explosion that kills the Martian and destroys his craft.
The Time Crash blog was created to help New Who fans understand Classic Who references - and to know if something isn't a reference but a new idea. If there's a reference I missed or a subject that you feel needs more explaining, please comment.