5 high school students get Saturday detention. One tries to find her sister's killer. When hit by a computer virus, the school goes on lockdown and the killing continues.5 high school students get Saturday detention. One tries to find her sister's killer. When hit by a computer virus, the school goes on lockdown and the killing continues.5 high school students get Saturday detention. One tries to find her sister's killer. When hit by a computer virus, the school goes on lockdown and the killing continues.