Shirlee was the subject of an experiment to enhance her natural agility and speed to superhuman levels.
Shirlee possessed superhumanly acute senses of smell, hearing, and vision. She also had superhuman strength, speed, agility, endurance, and healing ability.
The Cat’s costume is specially-designed to heighten its wearer’s natural athleticism. The Cat costume also had claws that could be used as weapons and as grappling hooks, as they could be fired from the costume with an attached cable.
University of Chicago Professor Joanne Tumolo was developing a process to enable a human being to attain his or her full physical and mental potential. Out of financial desperation, Dr. Tumolo had accepted private funding for the project from Malcolm Donalbain, an eccentric who secretly planned to create an army of women warriors to serve him. He chose Shirlee Bryant for the experiment. Not trusting the test subject that Donalbain had coerced her to use, Tumolo had her assistant Greer Nelson secretly undertake the experiment alongside the other woman.
When Bryant died in a test of her new abilities, Donalbain had his henchmen set off dynamite charges at Dr. Tumulo's laboratory to make it appear that Bryant had died accidentally in an explosion.