Our Lady of the Lake's Mabee Gymnasium will be illuminated by a holiday laser show this Sunday — and the spectacle is free of charge. Arts group Urban-15 will choreograph its annual display of laser beams and 3-D animations to a soundtrack of holiday hits and original electronic compositions. The show is the work of laser wizard Tim Walsh with contributions by George Cisneros. The group will present two shows, one at 3 p.m. and another at 7 p.m. Though admission are free, reservations are required, and slots are going fast, according to Urban-15.