 Prue is obsessed by the feeling that the Halliwell sisters are chased by a demon sent by the Triad, and Darryl, Piper and Phoebe believe she is exaggerating, since it could be a human. Meanwhile, the Triad sends the invisible demon Troxa to help Cole to destroy the charmed sisters. Prue prepares a trap around the Book of Shadow and Cole is hit, but he finds an excuse to justify his presence in their home. When they vanquish Troxa, the demon tells that Belthazor is also chasing them.