BtVS: Goldilocks

Buffy sighed. walking back from the magic shop, she knew who would be waiting at home, lingering under the tree.
spike.
that vampire that she knew and hated. what did he always follow her everywhere? 'today', she thought, 'I'll remind him who has the chip'. Sure enough, there he was. his long black leather jacket touched the floor- just barely."there you are!" As he sauntered over, the moonlight spotlighted him for a second. He was looking paler then usual, even a sickly green... "the little bit has been scared to death! lucky I was here when you weren't."

Buffy is faced with a monster problem when Giles forgets completely about a mysterious attack. But is it mysterious? Is it a bit to close to home? Have they faced it before?
Is it more than they think it is?
What is it?