Guild Wars 2 – Accusation

Head into the Upper City and enter into the instance to trigger the cinematic with Queen Jennah:
Logan Thackeray: “ Sorry to intrude, Your Majesty, but this can't wait. There's a traitor in the Ministry.”
Queen Jennah: “That's a serious accusation, Captain. You know the law. Can you provide the required evidence to back up your claim?”
Hero: “We're working on it, Your Majesty. Captain Tervelan confessed that a minister ordered him to reveal patrol routes to the enemies. The Scream Falcons died because of it.”
Minister Arton: “Impossible! A minister would never betray our soldiers. I wish this matter investigated immediately, Your Majesty. The Ministry's honor is at stake. Captain Tervelan's command is within my ministerial jurisdiction. I'm the one who works directly with him, I am the one impugned. I'm not guilty of these crimes your Majesty, I'm loyal to you, and to Kyrta. As a show of faith, I place myself completely in your hands.”
Jennah: “Thank you, Arton. The Shining Blade will take you into custody, and you'll be kept under house arrest while we get to the bottom of this.”
Countess Anise: “Logan, I remember that one Seraph transferred out of Tevelan's company just after the Falcons were ambushed – Sergeant Hal. He might know something.
Logan: “Hal? As I recall, he patrols the eastern edge of Divinity's Reach. Hero, why don't you find out what he knows? I'll guard the queen.”

After this cinematic, you can talk with Logan again to get a little more detail on the situation and his feelings some. Head on out of the instance and make for Eastern Divinity's Reach. It is not a long trip but it will take a moment, even with Fast Travel. Once there you will find Hal without too much trouble. Time for another cutscene:
Hero: Sergeant Hal? I need to talk to you about Captain Tervelan.”
Hal: “Merciful Grenth. I knew this day would come. Did Tervelan send you to kill me?”
Hero: “No, calm down. Thackeray sent me. But tell me: why would Tervelan want you killed?”
Hal: “I delivered Tervelan's private messages to the ministry and … to the woods. I didn't was who the were for, but … oh gods, I knew. I transferred out the moment I could. You have to believe me.”
Hero: “So that's how Tervelan communicated with the Centaurs. Who was his contact in the Ministry?”
Hal: “I don't know but Danksy might. She was a Falcon before transferring to the Lionguard. She's stationed at Black Haven now.”

Head on out of Divinity's Reach and make for Black Haven which is marked on your map. Once there you will find that the Haven is about to come under attack from a Bandit Raid. You can face down the 6 bandits outside the compound or you can head inside.

Once inside one the guards will tell you that there is hot oil you can pour down onto the bandits below. This works only if you are fast enough to get up the stairs and to the oil before the bandits really get inside. Even if you only get a few, it will help for those with less health and armor.

Either way, when the first attack is fended off you need to head inside and go for the mortar (you can also head over to them and attack them directly). Use that to launch a ranged attack on the mortars that the bandits are using. Some careful aiming and it will not be too long before all the mortars are dead. Once the attack has been fended off then the Hero can talk with Dansky. You will find her on the Southern Wall of Black Haven.
Lionguard Dansky: “Those bandits caught us off guard, but they didn't steal anything. It was as if they just wanted to kill people.”
Hero: “I suspect they were here to kill you, Dansky. I need to speak to you. I'm investigating accusations of treason related to the Fall of Falcon Company.”
Dansky: “You have no idea how glad I am to hear that. I always suspected Tervelan was was rotten, but I had no proof. Falcon Company was the finest unit I ever served with. If I hadn't been recovering from an injury, I'd have been with them that day.”
Hero: “You must know something. Tell me: did you ever see Tervelan meet with a minister?”
Dansky: “No. My job was to deliver messages for the Seraph. The ones I through from Tervelan were address to 'Minister Arton' – but I know for a fact that Arton never got those letters. After Falcon Company fell, I found out that the guy I'd been delivering them to didn't even work in Arton's office. Nobody'd ever seen him before. I delivered Falcon Company's last patrol route to that guy, too. After the unit was attack, I put it together … and I couldn't stay in the Seraph.
Hero: “Do you know the route they were to patrol?”
Dansky: “Sure. They were supposed to go through Kessex Hills. Here, I'll mark it on your map.”

This puts you closer to finding out the truth of your sister. You can also talk with Dansky again to get more of an idea of what happened and learn that some of the centaurs would take slaves and sell them. It will allow for a personality choice so choose well. This will lead to the mission, “Liberation”.