There's a dark, little-discussed side to large groups of people gathering for big sporting and other events -- from the Olympics to the Super Bowl to the annual College World Series in Omaha. It is an increase in human trafficking, particularly sex trafficking. During the June 14-24 baseball tournament, Catholic-related groups and other organizations planned to lead prayer sessions to raise awareness and bring the power of prayer to the issue. The prayer series is an ecumenical effort supported by the Archdiocese of Omaha. "The CWS is an exciting event for Omaha, but sex trafficking increases, with young girls trafficked into our hotels and motels," said Sister Celeste Wobeter, a Notre Dame Sister who helped organize the prayer series, with representatives of a number of faiths leading sessions in two-hour blocks from 6 a.m. to 10 p.m. at a Salvation Army chapel. People have been invited to join in the prayer at the chapel at any time, for whatever length of time they can, Sister Wobeter said. A website was created for the effort.