Black Orchid
Written by Terence Dudley
Directed by Ron Jones
The Tardis lands in 1925, near a railway station. It seems they were expected. A driver is waiting to take them to a mansion where folks are playing cricket.
The Doctor joins in and helps his team win. Yes, the cricket outfit he wears is finally used during a game of cricket.
People keep mistaking Nyssa for a girl they know named Ann. We meet her, and they are exact duplicates. OK, the hair isn't styled the same, but they are twins.
Later, everyone prepares for a fancy dress party. Nyssa and Ann dress in identical costumes, complete with masks so no people won't know who is who. At the party, they switch places.
The Doctor's curiosity gets the better of him (as usual). He goes exploring in the mansion and finds hidden passageways. Problem is, he can't find his way back out. During his exploration, he discovers the body of a murdered servant. At the same time, someone enters his room and steals the costume laid out for him.
At the party, Tegan teaches the guests how to dance the Charleston, something she learned in school.
The clothing thief pretends to be the Doctor. He dances with Ann, then takes her inside, where he tries to kill her. A butler hears this and tries to stop it. He is killed in the process. Ann passes out. Later, she awakens in her room, sees a man with many scars on his face and hands, then starts screaming and runs out.
The thief/murderer returns the clothes to the Doctor's room. He finds his way back, puts the clothes on and goes downstairs, where Ann freaks out. Since he's wearing the clothes and mask of the person who attacked her, obviously (in her mind) he is the killer. He is arrested. Despite his protests, including telling them about his Tardis and traveling through time, nobody believes him.
He does manage to convince them to stop by the railway station, but the Tardis has been taken.
Moments later, it is found. It was discovered by the police and they move it. They've been trying to get in, but their keys aren't working. The Doctor's is, though. He opens it up and everyone, including the police, go inside. They're starting to believe him now.
Scar-man kills again, then starts the place on fire. An associate of the police comes into the Tardis to say he's received a telephone call. There's been another murder. The Doctor offers to take them there in his Tardis, it'll be a lot faster. It lands on the grass just outside the mansion.
Everyone departs. Scar-man comes out and grabs Nyssa, then takes her up to the roof.
Scar-man's name is George. Once upon a time, he was Ann's fiance. He was kidnapped, tortured, and had his tongue cut out. Eventually he was rescued and brought home, but Ann was not told of this. He's been kept hidden by the lady of the house. Now, he's a killing machine.
The Doctor and another man rescue Nyssa. The Doctor convinces George that Nyssa and Ann aren't the same person and he's made a horrible mistake. As soon as George releases her, he jumps to his death.
Now that the murders are solved, the Doctor and his companions depart for new adventures.
* * *
When was the last time we had a good two-parter? It seems like Four had a single two-parter with the Sontarans, but that was pretty dreadful. The last one I can remember was the First Doctor story The Rescue, which introduced Vicki. It was a small, intimate episode with just a few sets used well. This reminds me of that. There are only a handful of rooms, costumes and such are reused, and other than the dress box at the end, there weren't any new props.
And boy it was done well.
Other than the Tardis (and really, you could take the Tardis out of this and not change a thing about the story), there's nothing science fiction about this. It's an old fashioned murder mystery. There are no aliens, no visitations, the planet isn't on a crash course for the sun, and for the first time since she joined the cast, Sarah Sutton as Nyssa actually contributes to the story. Take her out and there is no story.
It's quick, as most two parters are, with snappy dialog and I couldn't see any story padding at all. Well done.