Big Finish Doctor Who/Recap/S4/E07 Relative Dimensions/NEDA

The Eighth Doctor and Lucy Miller celebrate Christmas with the Doctor's granddaughter Susan and great grandson Alex. what could go wrong?

Tropes:

 * Continuity Nod: Lots to the time where Susan was on the show, also to Death In Blackpool and An Unearthly Child.
 * Timey Wimey Ball: The creature is loose and causing touble on the Tardis before it has been released chronologically.