''[=StrikerS=] Sound Stage X'' is a two-disc self-contained [[AudioAdaptation Audio Drama]] story, part of the ''[[Franchise/LyricalNanoha Nanoha]]'' franchise. Taking place three years after ''Anime/MagicalGirlLyricalNanohaStrikers'', it excluded everyone introduced before that, with the exception of minor character Mariel and revolved around a new incident that the heroes must handle.

What appeared to be an ordinary SerialKiller case that Enforcer Teana was investigating turns out to be something more sinister as ancient texts that speak of the [[NightOfTheLivingMooks undead]] SuperSoldier army of Mariage led by the Dark King Ixpellia are uncovered together with the identity of a terrorist named Tredia who plans to use them. With the threat of a ZombieApocalypse looming over the horizon, Subaru and friends must battle the Mariage, and locate both Ixpellia and the mastermind behind this latest terrorist attack before it's too late.

'''NOTE:''' Only general tropes for the series are listed here. For character-specific ones, check out the [[Characters/MagicalGirlLyricalNanohaStrikers character]] [[Characters/StrikersSoundStageX pages]].

!!''Sound Stage X'' provides examples of:

* AllThereInTheManual: The Sound Stage X Dictionary has additional information on the plot, such as how [="N2R"=] got its name and the implications of [[spoiler:Teana's partner being implicated as the killer]].
* AmusementPark: Marine Garden.
* AssholeVictim: The hotel owner is shown to have a shady past and sleazy personality before he gets murdered.
* AudioAdaptation: Unusually for the series, it actually has events with lasting consequences for canon.
* BattleAmongstTheFlames: Inevitable in any battle against the Mariage since the first step in any of their attacks involves torching the place they're in.
* BittersweetEnding: The Mariage are neutralized, but [[spoiler:Ix goes into a coma that could last from one to a thousand years, and Teana's partner is arrested, upsetting her and leading to her taking a leave of absence due to feeling responsible]].
* BusmansHoliday: The incident occurs when Subaru was organizing a mini-reunion for any Riot Force Six member she could get a hold of.
* ConsultingAConvictedKiller: Ginga and [[spoiler:Cinque]] must consult the imprisoned BigBad Jail Scaglietti in order to gather some important data on the Mariage serial arsonist case. Scaglietti only asks for [[LibationForTheDead enough Belkan wine to honor the dead]] [[spoiler:Due]] in exchange for his info.
* CouldntFindAPen: The Ancient Belka Psalms, which were written in blood on the walls of one of the murder sites.
* DarkerAndEdgier: To start with, this is the first time where InnocentBystanders are explicitly killed on-screen en masse.
* DeusExitMachina: All of the super-powerful old cast are off on their own missions, allowing the newer cast to take the spotlight.
* {{Dystopia}}: Orussia, a place torn by civil war where basic necessities are scarce, but weapons and ammunitions are plentiful.
* DugTooDeep: The UnderwaterRuins [[spoiler: containing Ixpellia]] were uncovered during the construction of the Marine Garden.
* EvilPoacher: Erio and Caro catch one in the track where they first appear. He was quite surprised to find himself being hunted down by a dragon in this day and age.
* HeKnowsTooMuch: The hotel owner gets murdered immediately after he realizes what's going on.
* ImpromptuTracheotomy: The murder victims were found with their throats stabbed.
* IronicEcho: Subaru flicks Ixpellia in the forehead when she's angsting, and tells her it's something you do to children who are being unreasonable. [[spoiler:Later, Ixpellia does the same thing to Subaru when she starts to cry about Ixpellia's impending coma.]]
* LensmanArmsRace: The booklet describes the Ancient Belka War as this, and mentions how this was the direct cause for its destruction.
* LineOfSightName: The name for [="N2R"=] [[spoiler:the Nakajima sisters' unit]] came from the part of the rehabiliation center where they stayed.
* LowerDeckEpisode: The Mariage case is the only major storyline in the entire franchise where neither the Three Aces (Nanoha, Fate, and Hayate), nor a certain clone of the last Belkan Sankt Kaiser play a major role--in fact, the Aces don't appear in it at all. As a result, it is a fairly grounded (by the series' standards) episode that offers unique insight into what most TSAB investigations that don't involve an impending apocalypse or two are like.
* MinorCrimeRevealsMajorPlot: What started as a SerialKiller and arsonist case turned out to be a terrorist plot to revive a Dark King and unleash an army of undead SuperSoldiers.
* MundaneMadeAwesome: Vivio going Full Drive to do a data search with MAXIMUM POWER.
* ParryingBullets: The [[NightOfTheLivingMooks Mariage]] has no need for DeflectorShields since they can block a barrage of Magic Bullets with a single [[BladeBelowTheShoulder arm blade]]. This Sound Stage also had a scene that had FragileSpeedster Erio using [[BladeOnAStick Strada]] to deflect physical bullets fired by an EvilPoacher.
* PsychicAssistedSuicide: How one person died in front of Subaru. She wasn't able to stop him despite his pleas to save him.
* PutOnABus: All characters from the Nanoha universe that appeared before ''Anime/MagicalGirlLyricalNanohaStrikers''.[[note]]except for Mariel[[/note]] And the "Magical Girl Lyrical Nanoha" title and logo too.
* SuperpowerfulGenetics: The booklet mentions that the Belkan Royalties directly invoking this, experimenting on their bodies to not only turn themselves into [[PersonOfMassDestruction Persons of Mass Destruction]], but to also ensure that their descendents would inherit their powers.
* TimeSkip: Three years after ''Anime/MagicalGirlLyricalNanohaStrikers''.
* WarriorPrince: The standard king during the Ancient Belka War, who are mentioned in the accompanying booklet as having turned themselves and their descendants into [[PersonOfMassDestruction Persons of Mass Destruction]] to better lead their countries as symbol of power.
* WhamLine: Ginga and [[spoiler: Cinque]] are interrogating Jail Scaglietti about the whereabouts of the current BigBad and drops this bombshell at the end:
--> [[spoiler: ''He died four years ago. He was devoured by the Mariage.'']]
* ZombieApocalypse: What Tredia was planning to start with the Mariage.