Dark Vengeance

Set in the wake of the Source's defeat, the Charmed Ones are all a little out of sorts: Phoebe misses Cole, who's away on a week of solitary reflection; Piper is overwhelmed juggling her household, her Charmed duties, and P3; and Paige is still finding her footing as the newest sister and a novice at saving the innocent.

When their magic starts failing at the worst possible moments, they discover a rival trio of dark witches is working to unravel the Power of Three once and for all. The 15th book in the Charmed tie-in novel series, set between the show's "Charmed and Dangerous" and "Marry-Go-Round" episodes.