The zoo is a favorite excursion for Joan and her four-year-old son, Lincoln, a place to share the lions, tigers and bears, the chattering monkeys. The outing is enhanced by a boy’s vivid imagination, dusk a reminder of the closing of the wild, a return to the clatter of the outside world, held in check only by a perimeter fence and distant traffic noises. Today the pleasant hours with Lincoln become instead a nightmare; as mother and child approach the exit, Joan spins around, running back into the zoo. The sounds she has heard today (balloons?) suddenly make sense, gunshots, the bodies of the slain and wounded littering the ground, their assailants nowhere to be seen.

Joan seeks the canopied woods as a place to hide far from the massacre behind them. Once there, she takes a chance and calls her husband, Paul, only then realizing the ringtone and the light on the phone can give away their hiding place. Paul has heard about a commotion at the zoo, but can’t get any nearer than the police blockade, frantic in his helplessness.

Phillips builds the tension through scenes of mother and child, Joan protecting Lincoln from the terror, the sound of gunshots moving closer. Joan grows more terrified with each new sound bringing the killers closer, the boy not yet aware of the danger around them. She urges Lincoln to whisper, wondering how long the child can tolerate such restrictions. Her efforts at distraction are successful for a time, her thoughts drifting to happy moments with this lively little boy, his idiosyncratic view of the world, the special language they share. Joan cherishes these moments, unsure if they will live past this night. Suddenly Lincoln is hungry, his docility forgotten with the demands of his stomach. It is impossible to quiet his demands, so Joan begins a nerve-wracking trek out of the woods and toward the light, the threat of exposure more likely with each step towards the illuminated concessions, music booming near snack-filled machines.

Slowly Joan makes approaches, urging Lincoln to be patient, aware that this area holds the most likely chance of discovery. The next few minutes are unbearable, save the purchase of snacks that quiet Lincoln and the unexpected discovery of others hiding from the gunmen. That respite is short-lived, a taste of safety before fear intrudes and one of the killers finds Joan, Lincoln, and two others, a teenager named Kailynn and retired teacher Margaret. That encounter offers some insight into the shootings and a promise the other gunmen will dispose of the three women and child.

Three hours pass, the entirety of the thriller. Hiding seems futile but their only recourse as the women sense the footfalls of the killers not far behind them, anticipating discovery. The tension is unbearable, the zoo echoing with random sounds, frightened animals, manic laughter, gunshots, the sheltering woods infiltrated by voices of the intruders relishing the chase. Joan is desperate to save Lincoln, unsure if he can keep still, prepared to do anything to save her son. Minor decisions turn deadly, every moment critical, Joan concerned that they haven’t been rescued. The traffic noises outside the fence are so near, she imagines she might scale it with her son, a futile plan. Everything is magnified in these three deadly hours, every move fraught with risk, the grounds indifferent to a carpet of dead bodies, a mother shielding her child in this nail-biting tale of hide-and-seek. Ready to visit the zoo?