Ignoring the specifics of what's said:
'Souya' arrives at the dungeon entrance, where Lana's 'party' just came out, immediately trip the elf bitch leader and point an arrow at her face.
She make a fuss and the guild master the Evetta came out.
Guild master also noice the not-Souya in him.
After asking the situation, Souya accuse them of having done something to Lana, and the elf deny knowing anything.
Guild master use his power to check, and note that there's no record.
The bitch was about to keep going, but guild master correct her that there's the document missing (I think the party document?) which is pointing to something suspicious.
Then the dog guy speak up that the elf betrayed Lana to the prince, and the party document is with one of the prince's people.
The elf start shouting, but dog guy just say "u backstab same race, u no trust worthy, I out" and the mage goes with him.
Souya want to go to Lana's location (10th floor) but he's only been to 5th floor at most, and the guild master offer to exclusively send him there this one time due to circumstances.
And before Souya go through, guild master ask for the name of the one possessing him.
He doesn't gave his name, but it's basically Hyures the one spoken of in the song in ch 8. (what he say is something like the coward who ran away shooting the great spider)
On 10th floor he run into the cat girl, and with Izola's distraction took her out (just smack with paralysis arrow) and Souya have Izola lead him to where Lana is.
Meanwhile the prince was doing the usual "you're so ugly you should be grateful a prince is about to bang you" egoistic prick line (i.e. the logic of a tsundere, except now rapey power trip)
Lana is struggling all the while.
The mage in the prince party walk closer and say something along the line of 'how bout I mind fuck her into a horny bitch with magic, ya?'
Then that bitch mage got arrow exploding her torso.
The knight do the usual 'show yourself coward'
Souya come out saying 'and a group of people trying to rape a girl isn't cowardly?' and challenge the knight
If he runs out of arrow, the knight win and he'll retreat, but if he win the challenge, HE'S GOING TO FUCKING SHOOT THAT PRINCE'S BALLS OFF.
The knight manage to block and get close and declare themself the victor,
But then Souya goes 'now hold on a moment' and snipe the prince from the shadow (the Souya they saw was a hologram) then the knight.
The knight ,revealed to be a beastgirl, beg that he can do whatever he want with her, but spare the prince.
Souya refused and knock her out.
The prince, paralyzed by the spear, try to threaten with his daddy
Souya shove that right back at him:
1. He came here via emergency portal, and the one who sent him have promised to forget about it. And officially he's just a newbie who's only ever reached floor 5 tops.
2. He already got Lana's party form back already, so next he just need to let them get killd by monsters.
3. Who would believe that a newbie adventurer would be able to beat the prince and his escorts?
'sadly' Lana stop Souya before he can go further and finish what he 'promised', saying that nothing happened since Souya came in time.
Izola also warns that there's reactions of other parties approaching, so it's best to recover the arrows and get out of here.
Souya left one last threat that if he try to do something to Lana again, he's going to do exactly what he promised earlier.