Instruments of Darkness
The Doctor and Mel have encounted Vervoids, pan-dimensional terrorists, Chronovores (Quantum Archangel), and eighteen-foot Chiropterons. She at least knows about the Daleks, Chelonians (Fegovy) and Marmossan Horde. They've visited the Eye of Orion and the Kurgon Wonder (Sirens of Time), but not Gallifrey. She estimates she's travelled with the Doctor for at least a year. They recently visited Australia where the Doctor "borrowed" a Volkswagon (Sleepy). The exercise bicycle now had a sheet over it and probably hasn't been used in a while. Mel is co-signatory to the Doctor's Coutts bank account (Birthright).
Mel considers contacting her parents. Bob Lines remembers her returning to them some two years prior to this adventure, however. She drinks coffee at one point "reacquanting herself with the evils of caffeine".
And at the end, Evelyn leaves with Mel and the Doctor, heading for 2000 via the scenic route...
Mel and Evelyn work especially well together in this adventure. Perhaps there will be more adventures including the both of them, possibly an audio?
This is the sequel to both Scales of Injustice and Business Unusual.