The Transit of Venus (audio story)

Publisher's summary
The year is 1770, and daring explorer Captain James Cook and his crew on the Endeavour are navigating the Pacific Ocean.

Into their midst come strangers: the Doctor and Ian Chesterton, who are believed to have come from Venus. But the TARDIS is lost to them - along with both Susan and Barbara - and Ian makes an enemy of the ship's chief scientist, Joseph Banks.

Why is Banks acting strangely? Could it be that the travellers are not the only visitors from the stars?

Cast

 * Ian Chesterton - William Russell
 * Joseph Banks - Ian Hallard

Continuity

 * Several mentions are made of the Sense Sphere, and of the telepathic enhancement Susan experienced there. Indeed, this is one of the few stories that rather hinges on Susan's budding telepathic powers.

Timeline
According to Big Finish this story occurs between The Sensorites and The Reign of Terror. This is a highly unusual position for non-televised Ian/Barbara/Susan stories. Typically, such stories, like Farewell Great Macedon, are said to sit between The Reign of Terror and Planet of Giants, because that's the only actual narrative gap while Susan is on board the TARDIS. What writer Jacqueline Rayner has done here is to force a gap where none actually exists on television. Listeners without access to either of those two televised episodes will probably not mind very much, but careful visual inspection reveals how improbable this placement is.

All of the regulars are wearing exactly the same clothes at the end of The Sensorites that they're wearing at the beginning of Reign. Thus, what Rayner gives us is the idea that all our regulars had an intervening adventure lasting several weeks on the open sea, and yet at the beginning of Reign their clothes, hair length, and personal hygiene are absolutely at the same level they were weeks ago on the Sense Sphere. Though such "magic" costumes and makeup were known to exist in Peter Davison's earliest season, the initial TARDIS team tended towards greater realism in their costuming. The regulars tended to look the same at the end of one serial as they did at the beginning of the following one. This implied that the stories were consecutive and that the viewer hadn't missed anything.

Tonally, too, the first scene of Reign is the "second half" of the last scene of Sensorites. When watched back-to-back, they are very much one scene, divided by a mild cliffhanger. Rayner attempts to make it all fit together by layering in a replica of the Sensorites/Reign argument. So, Rayner would have us believe:
 * the Doctor threatens to throw Ian and Barbara off at the next stop (Sensorites)
 * the Doctor does throw them off (Venus part 1}
 * the Doctor threatens to throw them off again (Venus part 2)
 * the Doctor does throw them off again (Reign)

It's clear that it's the production intent that Venus be nestled between Sensorites and Reign. Whether that actually works is a matter, perhaps more so on this audio more than others, for the individual listener to decide.