Yes… solve the greatest mystery ever… how is it possible Porter and John are actually married to other sentient beings?! Well we ARE. And we’re so confident in our marriages that we’ll allow them in front of a microphone where they could easily cry out for help. But they DON’T. In the final edit.
Anyhooo… it’s time for a Who-dunit and where else to start but with the all-time Queen of Mystery Writers, Dame Agatha Christie. The Doctor and Donna crash a party and come face-to-face with some classic mystery tropes (except for the part where the murderer is a giant alien bug). They’re name-checkin’ Christie novels left, right, and center as Porter, John, Mike, and Mrs. Probe try to unravel the puzzle that is The Unicorn and the Wasp.
We then slow the pace down – WAAAY down – as we stay in the 20s time period (in fictional terms) and time travel back (in production terms) to the 5th Doctor era (did everyone follow that?). Yes, the Doctor, Tegan, Nyssa, Adric, Paul, John, and Ringo suffer the horrible consequences of mistaken identity: attending a costume party! But not before there is some cricket. A LOT of cricket. So much cricket that it’s not really until Part 2 that we are presented with the Victorian Gothic thrills and chills of a secret-passage riddled house concealing dark family secrets. But it’s a good thing they got to it in Part 2 because there is no Part 3 or 4 and we wrap things up tidily(ish) without falling afoul of the curse of the Black Orchid.