Two-Headed Mary, the philanthropic panhandler who dresses like a society matron when she approaches theatergoers for donations to nonexistent charities, is missing. So is sidelined hoofer Billie Trask, who disappeared from the cashier's office of K. Jeffrey Welton's hit show Lucky Lady with the weekend take. Could either of them have followed a third Broadway babe, Fine and Dandy chorine Lydia Laurent--whose strangled, nude body, accompanied by two...