Many shows have some form of structure to their seasons, rather than just being [[GenreAnthology collections of stories.]] This article mostly assumes that the series in question are US full-length series of around 20-25 episodes with some to low SeasonFluidity. Even in cases of BritishBrevity, the season opening and closing episodes will tend to be similar in style to those in the US, regardless of the season's length.

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[[folder: Season Opener: ]]


This will often be big and spectacular, to lure viewers back to the show. It is not uncommon for new characters to be introduced to the show or for major plot changes to take place. See also {{Premiere}} and {{Pilot}}. It is also one of the most likely places to find a double length episode (and even when the first two episodes are both normal length, it's not at all uncommon for networks to show them back to back).

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[[folder: Lucky Episode 13: ]]


Some series only have the first 13 episodes of the first season commissioned, [[Front13Back9 with the promise of more if it is successful]]. For this reason, the writers will work out a 13-episode arc plot so that if the series is not renewed, it will still have a satisfying ending. If it ''is'' renewed then they need only rewrite the [[SeriesFauxnale final script]] or so to introduce another threat or more plot threads.

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[[folder: The Ep- 15 Shift: ]]


Episodes 15-16 of a season tend to fall around the time of (February) {{Sweeps}}, so networks will have big spectacular episodes to attract viewers. Plot shifts are not uncommon here, as these are the early installments of the "[[Front13Back9 Back 9]]" extension.

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[[folder: Season Finale (Ep- 20 to Ep-25): ]]


Again, big and spectacular, usually tying up all of that season's emotional and plot arcs, although an end of season CliffHanger is possible. There may well be character departures by various different means. In cases where the season finale is made prior to the decision on whether or not to renew the show being made, expect a finale that ties off most major plot threads, but leaves enough dangling to make it easy to carry on if the show is renewed.

If this is a two-season drama - even if the seasons are of irregular length - prepare to be burned.


!!Examples
'''Season Openers'''
* Horatio Caine's trip to Brazil in the Season 5 opener of ''CSIMiami''.
* Buffy and the gang starting college in the Season 4 opener of ''Series/BuffyTheVampireSlayer''.

'''Lucky Episode 13'''\\\
For examples, see Front13Back9

'''The Ep-15 Shift'''
* "Phase One" of ''Series/{{Alias}}'' is a textbook example.
* The nuclear explosion in season two of ''[[Series/TwentyFour 24]]''.
* ''Anime/{{Mai-HiME}}'' ended the Searrs arc in episode 15 (in a YourPrincessIsInAnotherCastle moment), and episode 16 introduced a new and unexpected plot twist.
* "Surprise" and "Innocence" on ''Series/BuffyTheVampireSlayer''.
* "The Coming of Shadows", a second season episode of ''Series/BabylonFive'', did this well enough to win a HugoAward. (It was actually episode 9, not 15.)
* Each of ''Series/{{Castle}}'''s three full seasons[[note]]It was a MidSeasonReplacement, so its first season is shorter[[/note]] has had a major two-parter with a big guest star representing a federal agency right about this time. They were:
** Season 2's Tick, Tick, Tick... & Boom!, guest starring Dana Delany, playing a specialist from the FBI.
** Season 3's Setup & Countdown, guest starring Adrian Pasdar, playing a member of the Department of Homeland Security.
** Season 4's Pandora & Linchpin, guest starring Jennifer Beals, playing a member of the CIA [[spoiler:& Soviet operative]].

'''Season Finale (Ep-20 to Ep-25)'''
* ''Series/DoctorWho'': "Bad Wolf/The Parting of the Ways", which ended with [[TheNthDoctor the regeneration of the Ninth Doctor]] into the Tenth Doctor and with Captain Jack Harkness being left behind on the space station. [[spoiler:The reasons for leaving Jack behind were not explained until towards the end of season three.]]
* ''Series/{{House}}'': Season 6 begins with [[spoiler: House's stay in the mental hospital, which mentions that he will be seeing his doctor for outpatient therapy after being discharged.]] This is not referenced again until a couple of episodes before the finale.
* ''{{Terriers}}'' is a textbook example of a season finale that works as either a cliffhanger for next season or a satisfying resolution to the series. (It turned out to be the latter when the show was not renewed.)
* TheHouseOfElliott, a three-season PeriodDrama with ten episodes per series and no finite plot, more similar to an American series than the typical British literary adaptation or original period miniseries, ended on a cliffhanger with one of the sisters threatening to walk out on the eponymous fashion house. However, the {{BBC}} then decided not to commission another series, so the series was left dangling.

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