Guild Wars 2 – Confronting Captain Tervelan

Head on into the Tamin Foothills. You will find an instance entrance in them that will start to lead you toward the location of Captain Tervelan. This will have the hero appear outside of a cave. Head on toward it and you will have 2 Ettins to deal with. These things are dangerous foes so handle them accordingly. Once you can, or have killed both Ettins, head into the nearby cave. This will trigger a cinematic scene with Tervelan:
Tervelan: “Of course you're still alive. Should've know a few centaurs couldn't kill the 'Hero of Shaemoor'. They're your specialty after all, right?”
Hero: “I know what happened to Falcon Company, Tervelan. How could you give them to the centaurs? How could you betray their trust like that?”
Tervelan: “I didn't want to do it. My soldiers were starving, our equipment was ruined. I had to do something or the centaurs would have killed us all. So, yeah,  I sold out Falcon Company so that some politician could say the Queen was a bad ruler. The rest of my command lived. I got funds to reequip my soldiers, munitions, decent rations, and a promotion. My command's killed more centaurs than the rest of the Seraph combined – thanks to Falcon Company's sacrifice.”
Hero: “And all it cost was one company of your fellow soldiers. You're not an officer, you're a greedy, lowlife thug. You'll pay for what you've done.”
Tervelan: “You and Bigsby … If you hadn't dug so deep, you both could've done a lot to help us. All of us. But now you'll just be ettin food. Bigsby may be already. This gate should hold you all in. I'm sorry it cam to this. Good-bye, 'Hero'. When you meet her, tell your sister I said hello.”

After that cutscene it is onto fighting another 3 Ettins. Thankfully they can be pulled one at time for those who are not so good at taking on tough foes simultaneously.  The final 2 are usually fought together so work carefully on them.

Once the ettins are down, head deeper into the cave to find and revive Bigsby. He will tell you that you can hurry and catch Tervelan. Once outside of the cave you will find Logan has made it to the scene. He will get Tervelan to surrender. Another cinematic will run:
Logan Thackeray: “Hey, are you all right?”
Hero: “Fine, Captain Thackeray. I'm glad you're here. Tervelan's a traitor. On top of two fresh counts of attempted murder, he was the one who betrayed the Screaming Falcons.”
Logan: “Bigsby's letter said as much. Then Tervelan kept insisting no one was in the cave, a bit too strongly for me to believe him. I'm glad you made it out.”
Hero: “Captain, I think Tervelan know something about the survivors of Falcon Company. I need to ask him a few questions..”
Logan: “By all means. Anything he can do to help redeem himself would be in his best interests. Life in prison can be rough on at traitor. You hear that, Tervelan? You'd better answer my friend's questions. It's a long way to prison, and the road could be very uncomfortable.”

At this point you can talk with Tervelan. He gives up who he was communicating with quickly. You can ask him a number of questions to get more details as well.  At the end of it you choose what you want done to him. If you are brutish enough, you will be given the option to kill him.

This will lead to “Accusation” back in Divinity's Reach.