Police are looking for a Scarborough teenager who they believe is in danger. Rachel Wallace, 17, left her house around 8 Thursday morning, telling her mother that she was going on a school field trip. A school official called the mother later in the morning saying Rachel never showed up. Rachel was last seen driving a 2001 blue Mitsubishi Mirage with Maine license plate number 2835SR. Police believe she might be heading to the Old Town area. Scarborough police will not say why they believe the teenager is in danger. Anyone with information should call 911.