From TARDIS Index File, the free Doctor Who reference.

Cover Art - Barry Piggott
Circular Time
Series:	Doctor Who - Big Finish Audio Dramas
Release Number:	91
Doctor:	Fifth Doctor
Companions:	Nyssa
Setting:	Spring: Summer: Autumn: Winter:
Writer:	Paul Cornell and Mike Maddox
Director:	John Ainsworth
Music and Post Production:	David Darlington
Publisher:	Big Finish
Release Date:	January 2007
Format:	4 Episodes on 2 CDs
Prod. Code:	6C/H
ISBN:	ISBN 1-84435-175-0
Previous Story:	Year of the Pig
Following Story:	Nocturne

Publisher's Summary

Summer to winter, the seasons turn.

In the springtime of a distant future, the Doctor and Nyssa become embroiled in Time Lord politics on an alien world. During the stifling heat of a summer past they suffer the vengeful wrath of Isaac Newton. In the recent past, Nyssa spends a romantic golden autumn in an English village while the Doctor plays cricket. And finally, many years after their travels together have ended, the two friends meet again in the strangest of circumstances.

Four seasons. Four stories.

Now close the door behind you, you're letting the cold in...

Cast

Spring

• The Doctor - Peter Davison
• Nyssa - Sarah Sutton
• Hoodeye - Jamie Sandford
• Redklaw - Toby Longworth
• Carrion - Lois Baxter
• Snowfire - Teresa Gallagher
• Zero - Hugh Fraser

Summer

• The Doctor - Peter Davison
• Nyssa - Sarah Sutton
• Guard - Jeremy James
• Molly - Sunny Ormonde
• Jailer - Trevor Littledale
• Sir Isaac Newton - David Warner

Autumn

• The Doctor - Peter Davison
• Nyssa - Sarah Sutton
• Andrew - Jamie Sandford
• Jack - Toby Longworth
• Anton - Jeremy James
• Don - John Benfield

Winter

• The Doctor - Peter Davison
• Nyssa - Sarah Sutton
• Lasarti - Jeremy James
• Anima - Sunny Ormonde

References

Spring

• The Doctor mentions needing to finding time to build a new Sonic screwdriver.

Winter

• Nyssa and her husband help the Doctor into a recreation of the Zero Room in his mindscape.
• The Master uses Kamelion's connection to the Doctor's TARDIS to try and prevent the Fifth Doctor's regeneration into the Sixth Doctor.
• There are mentions of Tegan , Turlough, and Adric.
• Nyssa and the Doctor encounter The Watcher in his mindscape.
• The Doctor comments on his next regeneration being very colorful, a possible reference to the Sixth Doctor's coat.

Notes

to be added

Continuity

• Nyssa and the Doctor make reference to the events of DW: Logopolis, as well as the cause of the Second Doctor's regeneration into the Third Doctor.
• The Doctor mentions the events of (DW: The Caves of Androzani), and Peri.

Timeline

Placing Circular Time within a timeline is some what complicated, given that it is in 4 parts. Thus the following is supposition based on the dialogue.

Spring

• Spring occurs at some point (early) after: DW: Castrovalva.

Summer

• Summer occurs at some point after: DW: The Visitation

Autumn

• Autumn occurs at some point after: DW: The Game.

Winter

• Winter occurs for Nyssa a long time after: DW: Terminus.
• Winter occurs for the Doctor just before/in between his regeneration in DW: The Caves of Androzani.

External Links

• Big Finish Circular Time page
• Doctor Who Reference Guide - Detailed Synopsis - Circular Time