Meet Sherman Holmes, an eccentric detective with a flat styled after his fictional hero, Sherlock Holmes, and his partner, John H. Garden, who harbors a secret life as his flamboyant alter ego, Joanne
Their quiet lives as private investigators take a dramatic turn when they attend a meeting of the Quaker Street Irregulars, a Sherlock Holmes appreciation society. The evening descends into chaos when a controversial member, Cyril Antony, attempts to read his salacious short story, "A Study in Cerise," which portrays Holmes and Watson in a scandalous light.

The next meeting, however, brings a far more shocking revelation: Cyril Antony is found dead, garroted with a violin string, a copy of his offensive manuscript tucked into his waistcoat. With the local police, particularly the skeptical DI Streeter, quick to eye them as suspects, Holmes and Garden must clear their names and solve the baffling murder. Can this unlikely duo unravel the truth before they become the next victims—or worse, before DI Streeter throws them in jail?