Survival of the fittest - Jeff Mariotte

Alien abduction fever has gripped San Francisco and people everywhere are reporting loved ones missing... only to have them show up at home, with no recollection of being gone. The Charmed Ones can't help but become involved, especially when Phoebe receives a letter to her column from a woman who's convinced her sister was "taken". The victim says that she was just out, but since returning she's developed an almost demonic devotion to a new fitness programme. As fitness fever grips the Bay the Charmed Ones suspect that something supernatural is at work, and so when the fitness fiesta comes to town, they figure it's the best way to find out who
or what
is in charge of the chaos... before it's too late!