Claire Malloy believes there is just one thing better than chocolate...and it's not jumping around in an aerobics class. Nonetheless, she gets roped into accompanying a chubby heiress named Maribeth to Faberville, Arkansas's hottest new fitness centre. Personally, Claire thinks the best way for Maribeth to lose 160 unnecessary pounds would be to dump her abusive husband. But while Claire's teenage daughter Caron unsuccessfully tries every fad diet she can find (as long as it doesn't mean cutting out pizza), Claire has to admit Maribeth's commitment to diet, workouts, and supplements is working...until things go horribly wrong. Besides becoming moonstruck over the big-muscled fitness instructor, Maribeth is acting loony outside the gym as well. And when she ends up "accidentally" dead, Claire starts to exercise her instincts for crime ...and hunt for a killer.