The "alternate" summary may be easier for you to follow...so scroll down to find it in this link.  The narrator is on his way to be with his friend who is in need.  His friend Roderick feels as though his days are limited and wants to spend his last days with his dear friend (the narrator). When the narrator arrives, Roderick looks deathly pale and "cadaverous." Roderick's sister Madeline is also awfully sick, and will most likely meet the same ending as Roderick.

The two men spend time together playing music and reading.  After a week, Roderick tells the narrator that Madeline is dead and he needs assistance in burying her.  They place her in a tomb a floor below where the narrator sleeps.  Before they seal her coffin up, they see the slight smile and blush in her cheeks that still remain in death. 

Over the next few days Roderick's health and demeanor decline.  The narrator, trying to calm him down one stormy night, begins reading "Mad Trist" to him aloud.  As he's reading, the narrator begins hearing noises coming from the tomb below them. Then Roderick shouts that they had placed her in the tomb while she was still alive. Then a strong gust of wind blows open the door and Madeline stands there covered in blood.  She lunges for Roderick, and they both fall to the floor together, dead. The narrator runs from the house.  As he turns back, he sees a large crack open up and the house crumbles to the ground and disappears.