Main •
Fletcher "Half" Moon (
Rory Elrick) – Fletcher is a teenage private detective who, at the beginning of the series, has just graduated from Bob Bernstein's
Online Academy For Investigative Excellence. He has the nickname "Half Moon" because of his small height. He sets up his own detective agency at St. Jerome's School with his best friend Red Sharkey. •
Red Sharkey (Sebastian Charles) – Red is Fletcher's right-hand-man helping him with his investigations. He is the eldest of his siblings – collectively known as the "Sharkeys". His mother died prior to the events of the series, the death is shown to weigh heavily on him. He is sent back a year to Fletcher's year group at the beginning of the series. •
Mia Stone (
Olive Gray) – Mia is the editor of the St. Jerome's School student newspaper. She frequently gets herself involved in Half Moon's investigations in order to get news pieces for her paper. •
April Devereux (Nicola Duffell) – April is the leader of the 'Pinks' girl gang and hates boys. She is shown to regularly plot against male characters in the series and manipulate the other 'Pinks'. She is from a wealthy family, her father is said to be a "generous supporter of the school" and is implied to own a food business. •
Principal Quinn (Jennifer Black) – Principal Quinn is the Principal of Saint Jerome's School who favours hardline discipline.
Supporting •
Zara (Rameet Sandhu) – Zara is April's best friend and member of the 'Pinks'. •
Mercedes (Marion Weaver) – Mercedes is another member of the 'Pinks' and is shown to be a talented pianist. •
Hazel Moon (Robin Milne) – Hazel is Fletcher's older sister. She is frequently cited by her brother as having "multiple personalities", changing her appearance, personality and interests to get closer to boys she's interested in at the school. •
Mrs Moon (Hilary Maclean) – Mrs Moon is Fletcher's mother and a nurse. •
Mr Moon (Gary MacKay) – Mr Moon is Fletcher's father. He tries to get Fletcher to be more interested in sports. •
Genie Sharkey (Kathleen Kidd) – Genie is Red's younger sister. •
Herod Sharkey (Marcus Nash) – Herod is Red's younger brother and the youngest of the Sharkey siblings. At one point in the series he is voted in as his year's representative. •
Papa Sharkey (Russell Anderson) – Papa Sharkey is Red's single father. He is shown to be a caring father, who struggles with the passing of his wife and keeping his children out of trouble. •
Doobie (Robert Carr) – Doobie is a student at St. Jerome's. == Reception ==