The episode opens as the Monkees are just finishing a rehearsal. There's a knock at the door, and it's Mr. Babbitt, the landlord, demanding the rent. Davy points out they paid it on the first of September, but Babbitt points out that was for July! Mike says they'll pay the rent when Babbitt fixes what he promised to fix, but Babbitt doesn't believe the house needs any repairs at all, but the rest of the Monkees point out what does need to be repaired. Babbitt leaves threatening to send his lawyer to evict the Monkees.
Mike figures that they don't have to be there when the lawyer arrives, they can be disguised as someone else -- Mike as an old man, Davy as an old woman, Mickey as a doorman, and Peter as a TV repairman. At least that's only until they realize that the lawyer that appears is there for about a legacy left by an eccentric millionaire, at which point they resume their normal identities again.
Next we have the opening credits! After the credits, the title comes up on an old castle-like mansion on an island, where the Monkees have been summoned. They arrive in their distinctive eight-button shirts, and are spooked by a bat, and then by the butler, Ralph. Ralph tells them that they were mentioned in the will of his late employer, John Cunningham. Mike doesn't believe that they even knew him, but Ralph says a long time ago, they returned a wallet to him containing $600. Micky assumes it's because it showed their honestly, but Ralph says it's because it wasn't Mr. Cunningham's wallet!
The Monkees are then introduced to the rest of the people mentioned in the will: Madam Roselle, Mr. Cunningham's spiritualist (whose crystal ball is a snowglobe); Mr. Kingsley, Mr. Cunningham's traveling companion (who's written books about all of his travels); and Miss Ellie Reynolds, Mr. Cunningham's grand-niece. Of course, she and Davy exchange glances, and get sparkles in their eyes (literally). Micky notes, "He's in love!" to which Mike responds, "Yeah, for the very first time today." Peter, unfortunately, is stuck as Kingsley asks if he's read any of the books Kingsley's written.
Ralph then announces that it's time to play the will, since Mr. Cunningham recorded it on a phonograph record (Mike: "It'll never sell."). Ralph plays the record, and Kingsley wants to skip ahead to where it's said that he'll inherit the mansion. Madame Roselle insists she is to inherit it, and checks her palm to verify (and indeed, it's written right there). To the Monkees, he's left the library organ so long as they play one song. Finally, he leaves the mansion to Ellie, so long as she spends one night there before deciding to keep it. The Monkees go to the organ to play it, and then we have our first romp!
The romp is to the song "Last Train to Clarksville," which was featured on the first Monkees album (and would also be used in the next two episodes). Shots include the Monkees playing on a merry-go-round (which was actually filmed for the pilot), the Monkees performing the song on stage, lots of stock footage of disasters from inventions that failed (like jetpack-powered ice skates), trains running on tracks, the Monkees driving the Monkeemobile (same shot as in the opening credits), riding a dune buggy on the beach, riding the unicycles with the training wheels, and riding minibikes. It's obvious in the scenes where the Monkees are performing the song that they all haven't quite figured out how to fake it -- Mike and Peter have no problems, they're actually playing (or pretending very well, even if Peter's trying to move around a bit more than the others are), Davy's shaking his maracas and tambourine, but Micky really hasn't learned the drums yet. Also, on the bass drum, they haven't gotten around to painting the Monkees logo on it, it just has a logo taped on it.
Madame Roselle, Kingsley, and Ralph eye the Monkees suspiciously -- it seems obvious they're up to something! The Monkees are ready to leave, but the last ferry was cancelled due to fog (It is, after all, their foggy season, which lasts from 1895 to 1975). Ralph shows them to their room, where the Monkees all dress in nightshirts (don't know where they came from, since they didn't pack anything, but this is 1960s TV, after all). They're all a bit spooked, and keep startling each other. All four Monkees share one bed, and as soon as the light is turned out, there's spooky sounds, and the wind blows the window open. The light comes back on, and Mike insists that they need to stand watch if they're to get any sleep. They decide to "shoot" for it, but keep tieing until one time, a gorilla hand joins them, sending the Monkees running out of their room and into the hall.
As they wander down it, Madame Roselle appears, announcing she's had a vision about the butler, he's going to take a long journey or he's dead. When Micky asks which it is, she says, "Six of one, half a dozen of the other." They hear gunshots and rush downstairs, where they find the room has been trashed, and weapons of all kinds have been in use (arrows, knives, axes and so forth are in the walls, there are bullet holes everywhere). They decide someone's been murdered, and when Kingsley and Ellie show up, they all realize Ralph is gone.
They decide to call the police, but the phone line's been cut, and tied into a bow (Micky: "Well, at least we know the murderer is very neat!"). Roselle says the house is full of evil, and Kingsley takes Ellie back to her room. Micky calls Davy over to look at one of the knives, and they do a Sherlock Holmes and Watson bit. They're interrupted hearing Ellie yelling "No!" in desperation, and rush to her, where they find that Kingsley's going through his whole list of books he's written, asking her if she's read them.
Micky figures there must be a way to get a message out. Mike's decided to put bread crumbs on a windowsill to attract a carrier pigeon to send a message out. Sure enough, one lands, and Mike's ready to strap a message to its leg... but there's already one on it! Mike reads it, and it says, "Please don't strap a message to my leg, I am not a carrier pigeon." Mike's next plan is to attract a St. Bernard by placing a line of bones to attract it (Mike explains he found them in a closet). Sure enough, a St. Bernard appears, and Mike's ready to put a message on his neck, but there's already a message, that says, "There is a message for you on the pigeon."
Later, the Monkees are finally asleep when they hear another gunshot! But Mike insists it's a car backfiring from the next room... but they all realize that can't be. When another shot is fired, they panic and start to flee the room, but Madame Roselle blocks the way with another prediction, she must warn Kingsley he's going t be shot in 10 minutes. When Peter points out they just heard two shots, she consults her watch and complains it must be slow.
So now, Ralph and Kingsley are both missing. Micky figures he could take the telephone and the radio and combine them and make a signal. At lightning speed, Micky hooks things together, and tries it. But he's only able to reach a Russian sailor. Madame Roselle decides to hold a seance to find out who the murderer is. The first spirit she reaches isn't the spirit of John Cunningham, but his answering service. Next, they get the Ghost of Christmas Past. Then the lights go out, and when they come back, Madame Roselle is gone! Of course, they all turn to the camera to say, "She's gone!"
At the wind-up, the boys explain to the police what happened, and the villains are arrested (Kingsley asking if they've read his books). The closing credits inform us that "Last Train to Clarksville" was written by Tommy Boyce and Bobby Hart, and "Tomorrow's Gonna Be Another Day" (misidentified as "Tomorrow Is Another Day") was written by Tommy Boyce and Steven Venet.