the tardis arrives near a vast space museum on the planet xeros, but has jumped a time-track. the first doctor, ian, barbara and vicki have a series of bizarre experiences as they venture outside and into the museum – not least that they see but cannot be seen by the militaristic moroks who run the museum, or the servile indigenous xerons who work for them. the museum contains fascinating exhibits, including a dalek shell, but the most worrying is the four travellers themselves encased and on display. quite soon afterward the time track slips back and, though the exhibits of the tardis and the four travellers vanish, they still find themselves inside the museum.