Open the envelope. Inside is a key and a number.
Walk that number of steps east from where the body is buried. Use the key to open the car door. There will be a satellite navigation system inside. It will already have a destination programmed. Do not travel to this destination. Look at the postcode. Move each of the letters down in sequence and each of the numbers up.
Travel to this destination. Do not loose the tooth.
This is the ritual.