Adventures in Skyrim - spoilers ahead! You can follow the rest of the story here!
Solving the puzzle brought me another surprise, as it freed rather fetching, elder scroll carrying vampire girl named Serana. My first instinct was to kill her but since she seemed disoriented and non hostile I thought I'd question her first. Simply put, she wanted to go home, and wanted me to take her there. Since it was unlikely it was going to be a trap, I decided not to pass up the opportunity to get the location of a secret vampire base. Back topside I decided to swing by Solitude to rummage through more of my gear, and to check in with Jordis and Njada who were a little curious as to who my new raven-haired, red-eyed, friend was before pressing on.
Turns out the "secret vampire base" is a bloody great castle just off the northern coast. How did anyone miss that? Anyway, we literally stroll inside (for some reason I can't go on a murderous rampage right now) and are welcomed by her father, Lord Harkon Volkihar and his court. As thanks he offers to make me a hideous monster (LOL). I politely decline and explain it was hard enough to cure my werecorginess so instead he banishes me back outside and warns me not to return. Naturally the first thing I try is to get back in there but I am defeated by their closed gate. With a sigh I decided to go to Skyhaven Temple to rummage for my things there and upon hearing of her friend Rayna's death, Alyssa asked to accompany me against this new threat.
Seems the vampires are on the ball though, because upon our return to the Dawnguard HQ we founnd it under attack by a small group of high level vampires. In a rage, Alyssa charged into the fray along with most of the other Dawnguard members (some new ones too). It was a massacre on all sides and in the end only the most powerful vamp, Isran and myself remained alive. I the chaos I didn't see what killed Alyssa the first time, but I certainly know what turned her into a pile of dust after she was raised as a familiar - Isran's gigantic warhammer. It was a long fight to defeat the last Volkihar vampire, and at the end Isran was in such a beserked state he kept trying to attack me too! I hid from him in his own fortress for a day (well, a cave behind the fortress to be exact) to let him cool off.
Apart from Isran and myself, only the newbie Agmaer and the two war huskies survived (because they stayed in the keep). It was no surprise then that my next task was to recruit two "specialists", a tamer and artificer, because Isran knew his group just got pwned.