Snakedance is the second serial of the 20th season of the British science fiction television series Doctor Who, which was first broadcast in four twice-weekly parts on BBC1 from 18 to 26 January 1983.
In the serial, the Mara takes over the bodies of the Doctor's companion Tegan (Janet Fielding) and Lon (Martin Clunes), the ruler's son, while seeking to manifest itself by using a crystal.
The young deputy curator Chela is more sympathetic and gives the Doctor a small blue crystal called a Little Mind's Eye, which is used by the Snakedancers, a mystical cult, in their ceremonies to repel the Mara.
The Doctor realises the small crystal and its large counterpart, the Great Mind's Eye, can be used as focal points for mental energy and can turn thought into matter.
Lon tries to persuade Ambril to use the Great Mind's Eye in the ceremony, placing it in a position that will enable the Mara to return.
The Doctor arrives in time and refuses to look at the snake or recognise its evil, relying instead on the still place he finds through mental commune with Dojjen via the Little Mind's Eye.
Originally the door for a third Mara adventure was to be left open, with closing scenes discussing the ultimate fate of the Great Crystal.
Brian Grellis was a late replacement for the part of 'Megaphone Man' after Christopher Farries dropped out of the production for unspecified reasons.
[4] In Doctor Who: The Episode Guide, Mark Campbell awarded it seven out of ten, describing it as "less experimental than Kinda" but still containing "some good moments", although he concluded that "Martin Clunes and Colette O'Neill are the best things in it".
He observed a "lack of genuine jeopardy, pace or thrills", but described the guest cast as "solid" and praised Janet Fielding's performance and Fiona Cumming's direction of the "surreal possession scenes".