Into the life of every TV series, a breather must fall. Here you have a successful plot engine chugging along, peopled by a beloved ensemble cast, all of whom who up every week to continue an ongoing story. But that can get tiring. Everyone needs a palate-cleanser.

Which is what happens when a showrunner and his or her set of writers step back and create what’s known as a “bottle episode.” The term refers to a self-contained episode within a series; technically, they’re supposed to be a money-saver since they rarely venture off of the main set (or even one room on the main set). But this is a lie – bottle episodes run over budget all the time.

What they really are is a chance for writers to crack their collective knuckles and go deep rather than broad with storytelling. The best bottle episodes are like one-act plays, taking place in an enclosed environment with a limited number of characters who may not do very much, but who undergo emotional or psychological changes. They are my favorite types of TV episodes.

Here are four that were done exceptionally well:

Star Trek: The Next Generation, “Data’s Day” (1991)

Written by: Harold Apter and Ronald D. Moore

Any discussion of the bottle episode would be remiss not to include something from Star Trek, the series that reportedly originated the concept (the “bottle” refers to a “ship in a bottle”; in this case, the Enterprise). In this episode, the artificial intelligence character named Data goes through a typical day in his life on the ship, narrated by his portrayer Brent Spiner. He experiences dramas small and large, but the script tells several small stories rather than a single overarching one that imperils a crew member/the ship/the universe. While no one would want to watch the heightened mundanity of a day in the life of a character each week, thanks to skillful writing and storytelling, plus the ultimate “outsider” character as narrator, the episode is charming and fulfilling.

Homicide: Life on the Street, “Subway” (1997)

Written by: James Yoshimura

How do you solve a murder that’s a kind of Schrödinger’s cat of a mystery? In this episode, which takes place almost entirely on a subway platform, commuter John Lange (Vincent D’Onofrio) is pinned at the waist between a subway train and the platform. His injuries are such that he cannot be removed without instantly dying, though whether he moves or not he will be dead within an hour. The detectives are tasked with trying to find the man who pushed him while also trying to keep him calm and track down his girlfriend so that he can make his goodbyes. The episode is moving and uncompromising – there is no last-minute save or easy ending. The best anyone can do is to find the not-yet-late man’s killer. The episode won a Peabody Award and earned two Emmy nominations (for the script and for D’Onofrio’s performance).

Law & Order: SVU, “911” (2005)

Written by: Patrick Harbinson

Though the show eventually leaves the Special Victims’ Unit precinct, most of the episode involves Det. Olivia Benson (Mariska Hargitay) speaking on the phone with a little girl who says she’s in a locked room. Tracking her down while calming her down is both harrowing and exasperating, but Olivia has to remain cool while marshaling all the forces of the unit to first determine it isn’t a hoax, then to actually locate the girl. Hargitay won an Emmy for her performance in this episode.

“When we finished the episode, I knew this was going to be nominated,” said then-showrunner Ted Kotcheff. “In 1967 I did a TV movie, The Human Voice, with Ingrid Bergman. She gets on the phone with a lover and off the phone. As her mood changed, the walls subtly changed colors to objectify her feelings…. The script [of “911”] did come to me because of [that film]: ‘Let’s put Mariska Hargitay on the phone for an hour.’”

Mad Men, “The Suitcase” (2010)

Written by: Matthew Weiner

Though not fully contained within Don Draper’s (Jon Hamm’s) office, the episode largely focuses on interactions between Draper and Peggy Olson (Elisabeth Moss) over one long night in which emotions get spilled and secrets are discussed. Both characters are going through life upheavals: The niece of Don’s friend is dying of cancer, and Peggy has sabotaged her relationship with her boyfriend by remaining at work. By the end of it they’ve had a rare (if brief) discussion about the baby Peggy gave up for adoption and Don has gone to sleep with his head in her lap. They’ve never been lovers, but in this moment they’re as intimate as two people in a long, meaningful relationship.

“In ‘The Suitcase’ you see a vulnerability from Jon,” Weiner said. “A lot of people look at that character and see someone who is reserved and a presence without dialogue, and to have an excuse to let go of that reserve and be adrift – he’s pitiful at times, he’s ashamed about having to break down his emotions, and that’s a satisfying thing to see him down… [With Peggy] you see this mutual respect between them.”

This article originally appeared at Curiosity Quills.