What I find to be stupid is the method they went for. Ruining the costume of the actress with the lead role? Seriously? That's not hurting her, that's hurting the entire acting troupe because now you have to delay the show while someone fixes/replaces the costume.
And if The Boss finds out it was you? You're gone. Because while the Troupe is used to a bit of drama (gotta have a dramatic personality to be an actor, after all), the line in the sand is where it starts to effect how well they can put on shows.
Yeah really, what was the plan, have a backup costume in your size made, what a sure fire way to get fired as it just screams I'm the culprit. Its not like it was her job to manage the outfits ether so no one will se it as her fault in any way. The only way this works is if she know shows and no one finds out why, which they even if she know shows it will get found out that the outfit is destroyed. This sort of crap only works in schools because the play isn't the lively hood of the teacher, its just side thing they hardly care about so they don't look into it any further and often in the schools the teacher make you responsible for your own costumes so they don't have to look into or deal with anything if one gets ruined like this. But that kind of laziness wont be present here.
There is a good chance they have a spare outfit for a backup person in case the lead got sick or somthing, but again that just makes the backup suspect number one, though there are cases of a member actually trying to make the backup look bad to remove them so they will look into it. Regardless in no way will this get her in trouble, it just hurts her emotionally at the cost of your job (if your lucky in that time period)
Hopefully MC is smart enough to not just fix it but to first show it to the boss then fix it.