On Valentine's day, two alternate timelines form after Frasier decides to try out speed-dating. In one of them, he meets a woman at Café Nervosa and begins showering her with gifts. In the other, the speed-dating fails and he becomes depressed.
At Café Nervosa, Frasier tells Roz that he is going speed dating, i.e. having brief introductions with twelve potential dates, and is torn between going there dressed in a suit or a sweater. Meanwhile, Niles is planning a Valentine's Day date with Daphne, having booked a weekend in Cancun for them after she cooks dinner for him. Frasier eventualy decides on his suit. As he gets up, he meets a new KACL employee, Mike, introduces him to Roz, and then bumps into an attractive woman named Monica, falls and wrenches his shoulder. She offers to take him to the emergency room and Frasier decides to use it as an oppurtunity to ask her out. In the other timeline, Frasier chooses the suit, but changes his mind and stops to change into the sweater. Consequently, Mike bumps into Monica instead of Frasier and asks her out and Frasier proceeds to the speed date.
- From this point on, the Frasier who chose the suit will be referred to as "Suit Frasier" and the one who chose the sweater as "Sweater Frasier".
Sweater Frasier has his twelve miserable speed dates and returns home. As Daphne returns home to practice cooking the Valentine Day's dinner, Frasier helps her bring her groceries in. He notices that she will be using cummin and informs her that Niles is terribly allergic to it. Frasier, depressed at the state of his love life, starts playing "I'm Through with Love" on the piano and singing sadly. Meanwhile, Suit Frasier comes home. Because of his shoulder, he doesn't help Daphne with her grocieries. He then calls Monica and books a dinner date with her.
Suit Frasier spends the week leading up to Valentine's Day showering Monica with gifts and poetry and sets up a date with her at a benefit on the big day, which Roz will be attending with Mike. Sweater Frasier, meanwhile, has spent the week moping at home until Niles and Daphne's incessant cuddling drives him to accept a blind date at the benefit. On the night of the benefit, Suit Frasier, who still has been sending Monica increasingly lavish gifts, prepares to leave when Niles suffers an allergic reaction to the cumin in Daphne's food and becomes unable to make the flight to Cancun. They are both upset at first - until they realize that she will have to spend the weekend treating Niles.
At the benefit, Monica begins to feel smothered by Frasier's excessive attention. At the same party, Sweater Frasier goes to the benefit to meet his blind date, who turns out to be an annoying woman he met at the speed dating. Meanwhile, Suit Frasier serenades Monica on stage with Oh Babe, What Would You Say?. After his performance, Monica breaks up with him, saying he made her "feel like a project and not a person". Frasier takes it in stride, telling Roz he probably saw what Niles had with Daphne and wanted the same thing. While Roz walks Frasier to his car, Mike bumps into Monica and strikes up a conversation with her.
Driving home, Suit Frasier listens to a "Best of Crane" broadcast and hears him tell a caller the old "it's better to have loved and lost than to never have loved at all" and agrees with himself. Meanwhile, Sweater Frasier listens to the same broadcast and says "what a load of crap". The next caller on the tape says she has a crush on Frasier, who says he doesn't date callers. Hearing this, both Frasiers drive to the caller's workplace to ask her out, merging the timelines.
The camera alternates between the Martins of both timelines; both are sitting and watching TV with Eddie in their laps.
- The title is a reference to the film Sliding Doors, which also featured alternate timelines ending in the same place.
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