The green-fingered sleuths are hired to work behind the scenes of a garden makeover TV show, but Rosemary has an accident while standing in for the programme's star and ends up in hospital. Realising someone is trying to sabotage the series, Laura teams up with no-nonsense presenter Quinnie Dorell to catch the culprit.

An archaeologist posing as Rosemary dies mysteriously during a dig for Anglo-Saxon artefacts in the grounds of Lord Engleton's stately home, presenting the duo with a fresh mystery to solve. The gardens are unaccountably blighted by yellowing, forcing the estate to close its gates to the public, and a second death suggests somebody will go to any lengths for a piece of British history.