Letters From Crispin

When Alice sleeps over Lola-grandma's house for Lola-grandma's hundredth birthday, she receives a mysterious letter from a boy named Crispin, who claims to be a neighbor. But there is no one her age for miles around, except for a boy named Jason.

Who is Crispin? What does he have to do with the haunted house across Calle Nuevo? And what connects the February Revolution to the hundred years before it?