Rosemary Boxer goes to visit her friend Daniel Kellaway, who suffers from eczema, to receive a cash grant for her university but is asked by him to investigate the dying trees in the grounds of his mansion home. Laura Thyme has left her home after being cheated on by her husband and goes to see her friend Sam, who is later killed in a car accident whilst driving home one night. After meeting one another and forming a firm friendship, Rosemary and Laura begin to investigate into the accident and the dying trees.

The newly formed gardening duo 'Rosemary and Thyme' are called to help pop star Nev Connolly design and create the gardens for he and his wife Patsy's new house. Whilst working on the grounds, all are shocked when a digger uncovers the skeleton of a horse, which Patsy suspects could be Arabica, a horse stolen from the stables where she once worked. That night, Rosemary is woken by the sound of a gunshot and hurries outside to find out where it came from. Joined by Laura, they discover that Nev has been shot dead. Returning to work the next day, Rosemary is intrigued by a cut in the ground. Digging around it, she uncovers the skeleton of a human hand...

Rosemary and Laura are called to Vincent House Health Spa to rejuvenate 'The Dell' a water cascade designed by a women named Fenella Gothe, who has since died. Fearing they may not be able to get the water running again, they are surprised when Frances Caldecott, the owner of the site, requests a whole new plant arrangement to the one her late husband Edwin originally chose. Rosemary is given a book entitled 'The Language of Flowers' written by Edwin before he died, but not published until recently. In the book, Edwin has documented how different flowers can symbolize a range of actions and emotions. Laura and Rosemary are invited to dinner with Frances and her children Kate and Jeff. When Frances doesn't arrive, the party are shocked to find her strangled in her study...

Rosemary and Laura are summoned to Bowden Grange Language College to solve the mystery of random dead patches appearing on the lawns. Whilst shopping in the town, Laura witnesses one of the college students named Angelica, accused of shoplifting. When Reynolds, the security guard, searches her bag he pulls out a knife and takes her for questioning. Back at the college, Rosemary and Laura are roped into searching for Angelica, who has since disappeared along with Felix the college handyman. Driving along the surrounding roads, the duo discover the body of Felix in a ditch, with his throat cut...

Rosemary and Laura travel across the country to assist Rosemary's old friend the blind Professor Mullins, who has asked them to look into the odd death of random patches of plants on his allotment. The duo accompany the professor to an allotment committee meeting to discuss the strange circumstances but are shocked to find that the allotments are to be sold to a building firm. The professor manages to force a vote on the decision to sell the land and saves the day, much to the disappointment of builder Mr Kelly and site owner Hugo Dainty. Returning to the allotments the next day, Rosemary and Laura discover the lifeless body of Professor Mullins in a hole near his allotment...

Rosemary and Laura go to the village of Baffington where they are asked by the vicar to clean up the local churchyard in time for the upcoming Medieval Fayre. They soon meet Mr Danvers, a medieval times enthusiast who tells them about his plans to buy a local site called Brockett's farm but has competition for the land from drugs firm Knussens. At a village meeting to discuss the matter, the co-owner of Brockett's farm, the long lost Malcolm Sutton turns up, vowing not to sell the property. When Rosemary and Laura return to the churchyard the next day, they discover Malcolm under a yew tree, with an arrow through his chest...