It would be very easy to point at the title, remember that it is a Sixth Doctor story, arguably one of the most self-important and arrogant of all the Doctors, and make some kind of joke how the title is a trap meant for him.
It’s not, and that is the closest I plan to come to making that joke.
Reclusive former movie star Myrna Kendal stopped making movies in the 1970s. However, when the TARDIS appears near the talk show set where she is giving an interview, she recognizes the Doctor and Peri more or less immediately as the Doctor apparently talked her out of finishing her last picture. Peri? Well, she gets Peri’s name a little wrong, and since the Doctor and Peri have never met this woman, that means they met in her past and their future. Crossing your own timeline is never good idea, but it looks like they don’t have much of a choice, so off to the 70s to investigate.
I will admit, I was amused when Peri talked the Doctor out of wearing his usual attire, and he agreed, going to find what he wore in the 70s and apparently spent the rest of the story wandering around in the Third Doctor’s wardrobe.
As it is, Myrna in 1970 isn’t very pleasant, the very image of a demanding star, complete with a browbeaten directer (later revealed to be her husband), a petrified young costar (later revealed to be…someone very important), a shifty doctor giving her some kind of treatment (later revealed to be the bad guy), and a lapdog (later revealed to be the most innocent victim in the entire story, to the point Big Finish, during it’s regular announcement of who was playing whom in the story, attested that no dogs were harmed in the making of the story).
And yes, “treatments” from a shifty doctor sure does sound like drugs. But it’s some kind of weird machine, one that the Doctor quickly susses out does something to the very fabric of time, such that it speeds up and slows down at random. A trip to the prop room turns hazardous when a long dead taxidermied elephant returns to life and an unloaded gun has bullets in it because it did have ammunition at other points in time. These things revert to normal later, but then a time bubble appears around the building, trapping everyone inside, as evidenced when the dog runs outside and turns to dust.
See? Innocent victim.
Oh, and the Doctor literally needs to be reminded the young costar exists. If Peri hadn’t opted to tell the girl to stand up to Myrna, she and the Doctor might have been able to take the TARDIS somewhere to get some help or something. But that just merged them into the bubble as well.
Fortunately, this is the Doctor, and he knows the shifty doctor’s machine is at fault! Meant to keep Myrna looking youthful, it actually split her into two people, the other being the young co-star, representing a timeline when she didn’t become a big movie star. Phsyical contact between the two fixes everything, even if it merges the two into one older body (the director husband too), the shifty doctor dies, and the Doctor and Peri can simply take Myrna and her husband forward in time about 25 years to cover up their sudden aging.
Well, that vanity trap didn’t catch the Doctor. Good for him.