Lincoln is a good boy. At the age of four, he is curious, clever and well behaved. He does as his mum says and knows what the rules are. `The rules are different today. The rules are that we hide and do not let the man with the gun find us.` When an ordinary day at the zoo turns into a nightmare, Joan finds herself trapped with her beloved son. She must summon all her strength, find unexpected courage and protect Lincoln at all costs - even if it means crossing the line between right and wrong; between humanity and animal instinct. It`s a line none of us would ever normally dream of crossing. But sometimes the rules are different.