This is it, True Believers! All is revealed in the pulse-pounding conclusion to "Sins Past!"
In the Goblin lair, Gabe triggers a recording in whih Norman Osborn explains that he is the Green Goblin and that he killed Gwen. He's prepared Goblin suits and a Goblin serum to enhance the twins' strengh and slow their rapid aging. At the hospital, Dr. Chapin tells Spider-Man that Sarah's body is rejecting blood transfusions. Spidey offers his own blood. In the lair, Gabe takes the Goblin serum. Later, Spidey wakes up, weak from the procedure, and Gabe, as the Grey Goblin, attacks him. Defending Spidey, Sarah shoots Gabe's glider, sending it out of control. It explodes and he lands in the East River. Spidey passes out, Sarah leaves, and MJ tends to Peter. Later, Gabe washes up on a beach, alive but suffering amnesia.