I think that if you're going to read a DDM novel for the first time, then it really should be one of these four. I think all of them are equally fantastic reads, and the Hitchcock films of the first two are also well worth watching. I think I may well end up re-reading one of these while I am away this week.
Probably the most famous of all of DDM's novels, the book opens with the immortal lines "Last night I dreamt I went to Manderley again". The heroine of the story escapes from life as a lady's companion when she meets the handsome widower Maxim De Winter, but life when she arrives at his house Manderley in Cornwall is haunted by the memories of his first wife. I love this observation about the book from the Virago website: "Not since Jane Eyre has a heroine faced such difficulty with the Other Woman"
489 Jamaica Inn
After her mother dies, Mary Yellan travels to Jamaica Inn to live with her Aunt Patience. However, she arrives to find an inn which no-one will visit, and filled with mysterious goings on. Her Aunt Patience is cowed by her Uncle. Mary suspects smuggling... This is a hugely gripping adventure story, almost like Enid Blyton for grown-ups.
490 Frenchman's Creek
Dona St Columb is tired with her life in London, and takes her children to her husband's estate in Cornwall. She quickly settles in, despite the concerns that her neighbours are raising about the presence of a pirate in the area. She meets a Frenchman...is he the pirate?
491 My cousin Rachel
The story is told by Philip, a man brought up in Cornwall by his cousin Ambrose. Ambrose left Cornwall for Italy, for the sake of his health, and there, causing Philip considerable jealousy, marries the Rachel of the title. Ambrose dies, unexpectedly, and Philip blames Rachel for the death. However, Ambrose never altered his will, and Rachel is forced to go to Cornwall to sort things out with Philip...