A Nasty old zookeeper, shifty and mean. Sea serpent monsters, longish and green Vanishing - gone - without leaving a trace. Yes, this would be a most difficult case! Olivia and "Jenny the Great" team up with Scotland Yard when Nessie, the Loch Ness Monster, goes missing. Using their Super Transducer Blaster to search for underwater clues, the girls discover more than a missing sea serpent. Can the "Lucky Penny Detectives" solve this aquatic mystery?