In this episode. Using a trail of hair and a suspect’s “modus operandi” to solve a mystery AND making a real lie detector AND uncovering the telltale signs of art forgery AND solving a crime with simple chemistry. Car Key Recovery Louisa and Jessica can't get home from their beach house because someone has stolen the car keys and hidden them. The pair piece together a series of clues to name a culprit and find the keys. The Lie Detector Dad's chocolate stash has been raided so Felix and Spencer embark on a hunt to catch the thief. The round up the suspects and subject them to interrogation, and their brilliant lie detector machine. Art Fraud Holly discovers her uncle's favourite painting is a fake. With Sachin's help she makes a convincing case against its authenticity and discovers the fraudster behind the skulduggery. Mystery Liquid Someone has polluted the dog's drinking water. Anette and Harry use a homemade acid-alkaline test to determine who the culprit was.