Yeah the four break into a castle that would be cool
This could be told by the characters after the event as they make sense of what's happened. They followed a cave to escape a Roc*1 attack or something. Following the cave which has a draft, they find it follows into a neglected man-made network of tunnels with doors and rooms. There are rats (possibly the rat king?) and minor quests like a 1st lvl dungeon game. Then they go up a level till they break into the civilised castle, but they don't know where they are.
Red could tell the story, which would have exaggerated violence and action. Possibly a song and dance routine Romance would be gratuitously plonked somewhere.
Then The Knight would summarise the whole encounter in a matter of fact way telling the blunt truth of the story and being more acutely aware of their mis-understanding and surprise at accidentally breaking into a castle.
The lower forgotten dungeons they entered from were dangerous but once they got into the civilised part, but the official dungeon part of the castle, the underlayers where it's grim and gritty, dangerous and dark. Guards and prisoners might have been misinterpreted as monsters from the lower dungeon the companions had just come from. Following the forgotten tunnels they could accidentally break into the prison, then fight all the prisoners (The Knight bashes anyone who give them trouble. If they try to grab any of his weapons he will fight them with that weapon sheathed. With this The Knight succesfully intimidates, nobody messes with him after this. He's relaxed and methodical, not fighting unless he needs to and keeping it to knock-outs.) Then they all break out of the prison and have to fight all the guards. Red will know the prisoners but be following, and Red would say hello to one or two she recognises. The prisoners will share a gasp as they all recognise her. This is after The Knights confrontations.
Somehow they figure out the situation and they have to explain themselves, or get locked in the dungeon.
The knight probably negotiates some good faith with the duke who owns the castle and they just about get away with it.
Summary:
- Nothing was learnt.
- Reds perspective is shown and dramatised.
- The Knights objective bluntness is shown, includes that if we had let Red through first her celebrity would have solved the problem instantly, The Knight realises probably.
Ref:
- 1 The Roc -- https://en.wikipedia.org/wiki/Roc_(mythology)