I look at them both — my TARDIS and her companion — and wonder, do they actually need me at all?
It's been half a month since they started travelling together, but things are still uneasy between the Doctor and Tangerine as they grow accustomed to their unique relationships with the TARDIS. But that detente looks ready to collapse when the three of them fetch up on a world where the air is physically still and thoughts have a way of getting out of hand.
Something wonderful is being born here, and it's looking for a progenitor. When it abducts Tangerine to find it, the TARDIS is forced to undergo a startling transformation to save her. A transformation that the Doctor is far from expecting nor is sure he can reverse, and one which potentially leaves them stranded forever when the architects of what has happened reveal themselves.
What happens as a result is going to change the relationship the three of them share forever and fulfil a promise made regenerations ago..
Tangerine has been in the TARDIS for half a month prior to the events of this story; she has killed seven times since first being embodied.
The Bottom Line
With events clearly building towards a version of the Time War that was the 8th Doctor's ultimate legacy across numerous media, external events conspired to make him yesterday's news and brought his story in the IAs to a fascinating and entirely premature end.