
HedonisticAspie |

Remember, in Skyrim the Dragonborn is caught in the beginning of the story and being carted away to be beheaded. Only a dragon's intervention saves the player character from death.
Sometimes stuff is just happening to set the stage and tone of a campaign.
Note that this cutscene sets up the entire adventure and is very clearly a session 0/first few sessions equivalent where it's all story setup for the campaign.
There is a big difference between 'hey, this is early story-establishing stuff, so you can't really engage with it that much' and 'we are multiple sessions in and I don't want you to win what is clearly a combat encounter because I have a story in mind and that requires you to lose here'.
Again, I encourage you to be more flexible and adjust your story a bit more to give more agency to your players in this specific outcome and build something from here rather than to just toss the encounter in the trash and force the outcome as originally planned, even if it comes with an apology.
One of the amazing advantages TTRPGs have as a story-telling medium is being able to work with your players to weave a narrative together. This isn't a movie where the characters aren't real people and the narrative is set, and this isn't a video game where player actions can be limited in impact on the story without issue based on genre.
As a GM, you magic powers are being able to change the ebb and flow of encounters and story on the fly based on what it seems would be dope to do at the time. Sometimes that is making an encounter winnable that wasn't planned to be that way and making adjustments based on if they win, and sometimes it's making every encounter in an area incredibly difficult to show how dangerous an area is or how underprepared the party currently is.
I believe this is easily salvageable to turn it into something the players could end up thinking is great instead of just just enforcing the same fate on them and hoping they all take it gracefully the entire way through.