Film concept: Black Rose

Basically, a Sherlocke Homes character who is investigating a village full of people under the same conspiracy started by this old woman who kills people to feed her roses. Each victim in the compost represents a rose that grows on the plant and they always grow black. The investigation goes on and he begins to realize that she's getting supplies from the butcher at night. Then he finds the mayor supports this since it brings tourists and revenue. As he pulls all the pieces he needs to confirm the allegations, he tries to leave town one night late but all the towns people have been watching him so as he gets close to the train he is killed by the villagers and made into a single rose by the old lady who fell in love with him during his visit.