Twin sisters Lily and Alana wear "Truth Collars"—green for truth, red for lie. Mom blindly trusts Alana’s constant green light and punishes timid Lily for every red flash. On Christmas Eve, Lily suffers a ruptured appendix, but her collar blinks red. Locked home alone as Mom thinks she’s faking, Lily dies. Three days later, Mom finds her body and a journal revealing the collar’s cruel truth.
