"Castra Solis. Who better than Flambeau to help with fire?"
Sounds like a plan. Korvin helps to pull her up on the mount and then head for the Castra Solis Portal.
((Elain is one of those names that can go both ways. In this case, Elain is a man. 
Unless Fiona is doing experiments based on the question Peregrine posted in the Ars forum))
As Korvin and Elain ride toward the portal, which isn't all that far away, they come under fire from maybe one or two archers. Riding closer to the portal it appears that their aim is becoming more accurate, as an arrow just brushed past Elain's ear.
Korvin will cast Circleing winds of protection until they pass through the portal
1d10=3 + 17 +2 = 22.
You're going to need to make two concentration rolls to maintain the spell until you and Elain are safely through.
Even trying to hand th reins of to Elain is going to be problematic[1].
[1]I'm assuming that Elain's being Offensive to Animals is negated for the mount, much like the horse doesn't object to the Gift. Elain isn't much of a rider, given that, so his handling of a horse is going to be very poor and distracting.
I sure had to bite my tongue when Saxonous posted about having to use the back door. 
They are easy, or at least I judge them to be. Page 82 of the MRB indicates Walking as Simple and running as Average. I'll go with riding a horse as in between those.
I'm handwaving ride skills, too, since I noticed Korvin doesn't have Ride as an ability.
Arriving from Harco, both you and Elain are quickly intercepted by some grogs assigned to watch the portal. "State your business." This particlar portal is about a mile down the mountain path from Castra Solis.
I have an urgent message for your Primus Garus. I need to see him right away.
"I'm sorry, that is not possible, we're currently under lockdown, as several key personnel have just recently disappeared." His manner isn't menacing, but you get the impression you're being detained, even though he hasn't said as much. "Once the matter has been resolved, we will be happy to escort you to the Primus. Until then, we invite you into our barracks, and out of the chilly night air." The invitation seems rather firm.
Korvin dismounts and heads towards the barracks.
That is because the Order is under attack from within. Is their a Mage I might see with some authority?
"I dispatched a runner as soon as you arrived. One should be along presently. Now, if we might return to the warmth of our barracks while we wait?"
Korvin will go to the barracks to wait. He will talk to the guards to see if he can get any more info.
About 10 minutes later, a figure familiar to Korvin pops into the barracks (literally and magically). It's Lucius, whom Korvin has seen on his visits to Castra Solis in the past. His back is to you, and he begins grilling the guard who detained you, "You said there was a Redcap that came from Harco. Did he give you any trouble with the detention?" His tone is business-like and efficient and he's apparently unaware that you're in the room.
"My lord, no, he is behind you, and he came willingly and quietly. He came from Harco portal and indicated a message for Garus and said something about the Order being under attack from within. He's behind you, my lord." The guard who spoke with you points to you over Lucius' shoulder.
Lucius whips around, his long white hair following his body a bit more slowly. When he sees you, "Korvin, you've picked a terrible time to arrive." He seems relieved that it is you, that his eyes are resting on a familiar face, but he appears incredibly weary. In times past he's been jovial and warm. Korvin can tell something very wrong has happened here.
"Greetings Lucius. I had hoped for a happier meeting but not all messages from Redcaps can be good news. What your guard says is true. I have a message for Garus. The Primus for all the other Houses save one are gathering in Durenmar now." Korvin pauses while he looks at Lucius' face. " By the look in your eye you would like to know which one is not been invited and that may surprise you. But I also need some help. Agents have attacked Harco and set fire to the warehouses. We need one or two Magi who are skilled in Ignem or Perdo to help put out the fires. Insatella has been badly injured. i will have to return to heal her and escort her to the meeting."
"I'm sorry what you ask is not possible. Garus is dead." At this the guards who detained Korvin and Elain express utter shock, "I trust these men, and I trust you, which is why I'm letting you know this now. Some of our men our missing, assassins lying in wait, no doubt. They've been with us many years, but we can't find them now. Regardless, the damage here is done, and so my House is only too happy to serve yours. Abide a moment and I'll return with some of my sodales best equipped to handle extinguishing fires."
He disappears and 5 minutes later reappears with three other magi.
"Take us to Harco, Korvin. We will do what we can to aid you and your House."
I'm unfamiliar with how your house chooses it's Primus. Has one been designated or is it too early to know?
Where the missing men Hoplites to House Guernicus?
Be warned that there is a lot of confusion in Harco when I left. The Agents of our enemy have fostered it to prevent the houses for organizing.
Korvin goes back to the Portal and attempts to go through.
"As with all things Flambeau: a tournament of some sort. There is an inner cadre amongs us who reside permanently at Castra Solis who recruit good candidates. To answer the other question, no, we have no members of House Guernicus here, why would you ask such a thing? What do you know? Tell me, now, or we don't go with you back to Harco." his tone is matter of fact, as if trying to determine if he has enough resources to spare, or is bringing enough resources to bear.
Do you know I left Harco and joined Mons Electi in the Normandy Tribunal. The head of that Covenant is Apollodorus of Jerbiton. He was once known as Xenophon of Tremere. I see by the look in your face you have heard of him. He had been in hiding for 50 years for because of his research on the Druesca scrolls. Guernicus is trying to assassinate him even as we speak. Apollodorus was convinced that Druesca scrolls were genuine and that Guernicus is trying to take over the order. I would not have believed it 2 hours ago but I believe it now. My understand is that Garus knew of this. Insatella did not. I had to get her to open a message left by the previous Primus of my House.
I understand it is hard to grasp but think of this. Harco is attacked and the portals are disrupted at the same time, Coeris is attacked and your Primus is assassinated and other members of your House disappear. Those are just from the three Domus Magna that I've visited tonight.
If you think you need to alert your brothers I understand. But we need your House.
Do you know I left Harco and joined Mons Electi in the Normandy Tribunal. The head of that Covenant is Apollodorus of Jerbiton. He was once known as Xenophon of Tremere. I see by the look in your face you have heard of him. He had been in hiding for 50 years for because of his research on the Druesca scrolls. Guernicus is trying to assassinate him even as we speak. Apollodorus was convinced that Druesca scrolls were genuine and that Guernicus is trying to take over the order. I would not have believed it 2 hours ago but I believe it now. My understand is that Garus knew of this. Insatella did not. I had to get her to open a message left by the previous Primus of my House.
I understand it is hard to grasp but think of this. Harco is attacked and the portals are disrupted at the same time, Coeris is attacked and your Primus is assassinated and other members of your House disappear. Those are just from the three Domus Magna that I've visited tonight.
If you think you need to alert your brothers I understand. But we need your House.