Wagner tumbles out the window (Acrobatics 25) to arrive next to Oriace and the fleeing Zhent. He will also wrestle the Zhent (Unarmed Strike Grapple DC 11) and cast Hunter's Mark on him in case he flees. 

Oriace tumbles out of the window, taking 1 (halved to 1...) point of damage and not landing prone. He's able to reach the man who goes to deftly escape the grapple (25 acrobatics) but due to your spell, fails to avoid it (8).

Mana successfully blinds the man, hindering an escape (or can change action seeing Oriace succeed).

Wagner can tumble out for 1 (halved to 1) damage and not prone if he wishes. But seeing Oriace grapple can also choose to change his action. 

Wagner assists Oriace with the grapple, looking around if there is any way to drag the Zhent back onto the manor's property.

The quickest way back in would be if someone (Mana) unbars the door in the pantry that leads outside. The street south of the manor where that door leads is less busy than the north street. You might look a bit suspicious but it's not like the watch aren't going to investigate the manor anyway.

If you want to try and make it look like you are "assisting" the man into the manor, I want a straight deception roll from one of you (I assume one of you would help the other, and the Zhent is giving disadvantage).

There are no rules for a two person grapple but I will make some now that apply for this game. You cancel out the 'difficult terrain' effect of moving (with both of you dragging, you can move full speed, providing you move together). Additionally escape attempts are at a disadvantage and must meet the higher dc (11 in this case). I will also allow one of you to use an action to bind the man if you have rope on you with a slight of hand roll. The new escape dc will be the higher of the grapple dc and the slight of hand roll. 

Surprisingly (seeing as you can feel he is very acrobatic. With a +6 modifier) on this round he fails to escape. So you can start bringing him round. You are 40ft from the corner of the manor. And then 90ft from the door. 

"Come now, you always get surly when you are in your cups, you really must sleep this off!" Wagner says while pulling him to the door. "Mana, can you get the door?"

Wagner has no rope, so Oriace would have to do the binding.

Mana uses his Dash action to bolt down the stairs and unlock the pantry door. As he starts, he shouts to the surviving guards, “They caught him!”

With a dash you make it half way through the great hall. A dash on your next turn will make it to the door. (but with 130ft movement to go, you will still beat the others even if the Zhent does not escape) 

Oriace locks his grip with Wagner’s and hustles the blinded Zhent toward the servants’ door, keeping low and quiet; a quick thought flickers across the link—'Pantry door if you can, friend. Your shadow sphere might be useful, too.' He brakes with a soft grunt. “Hold a tick,” he rumbles to Wagner, fishing a slim coil of rope from his belt. Dropping to a knee, he whips the rope round the thug’s ankles, working a tight pair of half-hitches and a biting wrap meant to cinch under strain, then hauls the line to test it before rising and heaving forward again toward the corner. (Sleight of hand (DC 10): rolled 12)

End of round:

Mana: 60ft from door.

Others: 100ft from door. Escape DC increased to 12. 

He tries to escape. And rolls a successful save. I assume silvery barbs gets cast. And with that, I roll a 5+6 so 11. The rope just stops him escaping. And a nat 1 on blindness save. 

Next round, Wagner and Oriace can either both use an action to dash, or one of you can use an action to attempt to tighten the ropes with a new slight of hand. The ropes are long so you won't be undoing any knots, just tying new ones so the escape DC won't decrease.

Mana will be able to reach the door with a dash. But won't have an action free to unlock it 

Oriace snarls a low, steady note as the Zhent suddenly surges—'Not today'. He drops to one knee, fingers flying to add fresh wraps and a locking hitch over the ankle line, hauling the cord until it bites. “There,” he rumbles, rising to his feet. “Move.” He shoulders back into the drag with Wagner, boots skidding as they muscle the captive another thirty feet toward the servants’ door. (Sleight of hand: 9, or in spoiler if Wagner helps)

 [I registered the spell slot used for Silvery Barbs.]

[[Not sure what my meaningful choices are here. I can't dash as Oriace did not, I'd help with the knots but that is kinda pointless. If I could independently roll my higher slight of hand modifier, I got a 15.]]

Quote from Charwoman_Gene >>

[[Not sure what my meaningful choices are here. I can't dash as Oriace did not, I'd help with the knots but that is kinda pointless. If I could independently roll my higher slight of hand modifier, I got a 15.]]

[Sorry, I should have checked skill bonus before committing. If' I had done that, I'd have offered the help action instead of rolling. A different, arguably very unconventional, option would be casting invisibility on the thug. He wouldn't know as long as he's blind, but we wouldn't look as guilty as we do now. If he breaks from the grapple and the restraint, though, he would get away easier (no Silvery Barbs, too), unless he runs blindly into the wall. Unconventional and not without risks... It would also break concentration on Hunter's Mark... Altogether, I'm not sure it helps much.]

(I've already thought about running blindly into the wall if he escapes. I'll be rolling for direction he runs in) 

As cyreon would have let Wagner attempt the knot based on skill sets, I'll go with the 15 as the new escape dc. And I will wait for confirmation Mana dashes (as Mana will also know that there he will beat them to the door, so if he wants to take a different action this turn he can, or has another way to close the distance and get the door open this turn) 

Mana continues his Dash to the door.

(Neither the Dancing Shadows nor the Blindness requires concentration. The aura should spill into the street once he gets the door open.)

Mana is at the door. The thug tries to break free of the grapple, with a 15 acrobatics (at disadvantage) so is currently not grappled (but is restrained by the rope). (if silvery barbs is cast, new roll in spoiler). Without the grapple, you can't move him. After this round you are 70ft from the door.

Mana opens the door as an action (any movement?). And I assume the plan is to try regrapple and carry moving him.

Wagner re-grapples the thug, and attempts to move him 30 ft. if the grapple takes hold. DC 11. (Str or Dex, has disadv on dex due to restrained)

Mana steps out into the alley/street and moves towards the struggling trio. The sooner they’re obscured, the better.

(OOC: Apologies, I had to meet a deadline for work and couldn't keep up posting the last few days.)

Oriace snaps a sharp, discordant note—“Not so fast”—casting silvery barbs in vane as the Zhent twists, then lunges back in, arms locking low around the man’s hips to reestablish the hold. “With me,” he rumbles, bracing his stance and driving forward step by dragging step toward the servants’ door in synchrony with Wagner's efforts. He reaches out along the mind-thread—Mana, we’re——and feels the link fall short with Mana apparently still farther away than 30ft, jaw tightening as he digs in and hauls harder.

Reaction: silvery barbs (and will do again if the thug breaks restraint and/or a newly established grapple)
Action: grapple

Only the Dex save has dis from restrained. Str is a straight roll (but at the same time, dex saves are +6, str are +0).

Against Wagner, Nat 1 so 7 (fail)

Against Oriace, rolled an 18 and 19 (before modifier) so only singly grappled and therefore can be moved using nornal grapple of half movement.

At the end of the round, you are 55ft from the door, Mana having come out 30ft so you are 25ft apart now.

On the thugs go, he attempts to break free of the grapple, getting a 12 (after silvery barbs) so free once again. This time Mana can reach you. I've rolled two saves, and they both fail (10, and 8 with disadvantage) so whichever two of you grapple can then move 30ft to end with 25ft from inside. The other person has a free action 

Bump (need you to confirm if the third person not grappling, whoever that is, does any specific action)