TLDR:
Deathsquad vs Syndicate (everyone else) base, with the following rounds being War-Ops retaliation or revenge (based on the success of the NT attack). It will be heavy combat focused, but with a narrative that carries over a few rounds.
General Idea:
After losing numerous stations in the sector to Syndicate operatives, Nanotrasen has finally located one of the Syndicate war bases where nuclear operatives plan and launch attacks from. A Deathsquad has been sent to decommission the station, whether through killing everyone or using nukes.
But a traitor on board the Deathsquad shuttle or on Central Command (like the pilot who is then executed on-sight or handled via a Central Command announcement/message) sends a signal back to the Syndicate base letting them know NT is coming.
From here, it will be a high-combat round with the syndicates trying to kill the invading Deathsquad. The result of the match will determine the next rounds:
If NT wins: Desperate Syndicate remnants launch a standard Nukies/Warops round for pure revenge.
If Syndicate wins: Empowered by their victory, the Syndicate launches a heavy traitor/Warops retaliation round against NT.
*I envision this scenario having announcements from the syndicates either revenge or gloating. Additional Nukies could be sent, as well as Nanotrasen only being able to send guns, etc. due to limited resources from the attack.
Requirements/Setup Notes:
This needs a Syndicate Base big enough for the rest of the crew to defend. The standard Nukies spawn station is likely too small, so a new station or a current station remodeled in syndicate paint is needed.
Potentially a fair bit of setup time, as each syndicate crew member needs to get set up as a traitor/nukie and buying gear takes time. The Deathsquad can be distracted at Central Command with the leak/advisory to give them time.
The following rounds will take less moderation work, going into a somewhat normal nukies or heavy traitor round based on the story, (with maybe some extra flavour CC/Syndicate announcements).
Optional Extension: If you wanted a longer main event, multiple DS attacks on syndicate stations can be set up.