Time Reef is a Big Finish Productions audio drama based on the long-running British science fiction television series Doctor Who.
It is a three part adventure, released with the single episode story that follows it, A Perfect World.
The Doctor and Nyssa have returned to the TARDIS to find it missing various pieces of equipment and its dimensions unstable.
Thomas Brewster refuses to explain where he has been since he "borrowed" the TARDIS and what has happened to it.
Drawn by a distress beacon, the TARDIS crash lands on a time reef where the interior subsequently implodes, leaving the companions stranded.