Her true scheming nature is hidden from everyone except Shirley and Bo. Although her machinations are routinely thwarted by Shirley, Molly manages to escape punishment. She is revealed to be a sociopath in "The Case of the Crooked Comic" and is a mastermind of evil genius with an IQ of 160. Molly first appeared in "The Case of the Ruby Ring." It is possible that she is in fact descended from Professor Moriarty. Annick Obonsawin as Alicia Gianelli: Alicia first appeared in "The Case of the Ruby Ring". Alicia is a good friend of Shirley and Bo, and she works at the Quazar Cafe, often mixing up orders of her customers. However, she also bows out easily to peer pressure and appears more simple-minded and materialistic than Shirley is. Brendan Fletcher as Sterling "Stink" Patterson: Class clown and prankster. His parents run the local novelty store. If Molly is Shirley's 'Moriarty', Stink could be considered her 'Sebastian Moran', though while being a trouble-maker he is far less malicious. Stink first appeared in "The Case of the Ruby Ring" and his last appearance was in "The Case Of The Crooked Comic". Blair Slater as Bartholemew "Bart" James: Bart first appeared in "The Case of the Ruby Ring." He is highly interested in the paranormal and considers it good fortune to be abducted by aliens. He is also very concerned about his studies, as seen when Math is taken out of the curriculum in Sussex during "The Case of the Calculated Crime". He may be a little queer, but Bo and Shirley still treat him as a friend, and he is aware of Shirley's sleuthing activities and sometimes helps out. Chris Humphreys as Robert Holmes: The great-nephew of Sherlock Holmes. Mr. Holmes first appeared in "The Case of the Burning Building." He is Shirley's father. He is mostly worried for his daughter because he knows her tendency to get involved in cases out of curiosity, and at first he had almost given up hope on finding his wife. Elizabeth Shepherd as Peggy "Gran" Holmes: The niece of Sherlock Holmes. Shirley's grandmother and Mr. Holmes' mother. Marie Stillin as Ms. Cynthia Stratmann: Headmistress of Shirley's school, Sussex Academy, an upright woman who always works hard to success. She appeared since first episode, The Case Of The Burning Building, where she caught Shirley arriving late to class, therefore giving her detention where she ended