The Case That Time Forgot

Xander's classmate karim tells him about a famous amulet carved in the shape of thoth, the egyptian god of time. It was thought to be so powerful that it could turn back time one day every hundred years. And that day is in a week! When the amulet disappeared from a london museum years ago, sherlock holmes tried to find it but had no luck. now xena and xander are on the case and so is someone else. are the twins in danger?