The Sirens of Time (audio story)

"The Sirens of Time" is the first in the series of Doctor Who Doctor Who Audio Dramas produced by Big Finish Productions. Written and directed by Nicholas Briggs, the four-part story features the Fifth, Sixth, and Seventh Doctors, with Peter Davison, Colin Baker, and Sylvester McCoy respectively reprising their roles from the original television series.

Publisher's summary
Gallifrey is in a state of crisis, facing destruction at the hands of an overwhelming enemy. And the Doctor is involved in three different incarnations - each caught up in a deadly adventure, scattered across time and space. The web of time is threatened - and someone wants the Doctor dead.

The three incarnations of the Doctor must join together to set time back on the right track - but in doing so, will they unleash a still greater threat?

Cast

 * Fifth Doctor - Peter Davison
 * Sixth Doctor - Colin Baker
 * Seventh Doctor - Sylvester McCoy
 * Commander Raldeth / Schmidt - Andrew Fettes
 * Coordinator Vansell - Anthony Keetch
 * The President - Michael Wade
 * Elenya / Helen / Ellie / Knight Commander Lyena - Sarah Mowat
 * Ruthley - Maggie Stables
 * Sancroff - Colin McIntyre
 * Commandant / Lt Zentner / Pilot Azimendah / Sub-Commander Solanec - John Wadmore
 * Captain Walther Schwieger / Edifice Captain / Knight 2 - Mark Gatiss
 * The Temperon - Nicholas Briggs
 * Delegate - Nicholas Pegg

The Doctor

 * The Fifth, Sixth and Seventh incarnations of the Doctor make telepathic contact with one another to apprise one another of the situation through the spoken command "Contact".

Individuals

 * Tegan and Turlough are trapped within the Doctor's TARDIS when he arrives.

Organisations

 * Coordinator Vansell is a member of the Celestial Intervention Agency.

Races and species

 * The Knights of Velyshaa appear.
 * The Temperon is a legendary time beast, it is a 'cousin' to the Chronovores.

Theories and concepts

 * The Laws of Time (supposedly) stop the Doctor's incarnations from meeting.

Sirens' altered timeline

 * The Doctor prevents the RMS Lusitania‎ from being sunk.

Continuity

 * The Fifth and Seventh Doctors meet/met in MA: Cold Fusion.
 * The Knights of Velyshaa are mentioned and a Knight appears in BFDE: Invasion of the Daleks.
 * Vansell reappears in BFA: The Apocalypse Element and Neverland.
 * According to Instruments of Darkness, Evelyn was in the TARDIS while the Doctor was at the Kurgon Wonder.
 * The method through which the Doctors telepathically contact one other ("Contact") was first seen in DW: The Three Doctors.
 * Sancroff is mentioned by Kalendorf in BFDE: Dalek War: Chapter Four

Timeline
For the Fifth Doctor:
 * This story occurs after ST: Lily
 * This story occurs before ST: Qualia

For the Sixth Doctor:
 * This story occurs after BFA: The Marian Conspiracy
 * This story occurs before BFA: The Spectre of Lanyon Moor

For the Seventh Doctor:
 * This story occurs after NA: The Room With No Doors (after the Doctor returns Penelope and Joel home)
 * This story occurs before PDA: Bullet Time