As the new charmed one comes to terms with her powers, she finds herself resistant to accepting her destiny. Mel becomes protective, while Maggie is apathetic and aloof.

One last mystery holds the key to saving the world, and Grace must choose how she spends her final days.

An MIT grad student and a tech superstar bring a low-level Pentagon official a staggering discovery that an asteroid is just six months away from colliding with Earth.