The mitford murders

Louisa is a poor girl who lives with her mean uncle.
Luoisa jumped off a train to escape her uncle. She meets Guy who is a police officer. He helps her get a job as a nurse at the Mitford house.
Florence Shore is murdered.
The detectives do not care much about the murderer. Guy cares and he risks his job to find him.
Nancy thinks the killer is Roland because he killed his friend. She thinks he killed her uncle but he did not.
Louisa looks through Roland's stuff because she has a fishy feeling about him. This gets her fired.
Roland comes to Nancy Mitford's 18th birthday party. He asks her to marry him.
Louisa brings Mabel who saw Florence's murder. She will tell if Roland is the killer or not.
Nancy realizes Mabel is the killer. Mabel pulls out a knife.
Roland, Guy, and Nancy come to the rescue. Guy arrests Mabel.
Louisa and Guy express their love for each other.
If Louisa or Guy did not do what they felt was right, they would never have solved the mystery.