• Footsteps in the Dark (1932)
• Why Shoot a Butler? (1933)
• The Unfinished Clue (1934)
• Death in the Stocks (Merely Murder) (1935)
• Behold, Here's Poison (1936)
• They Found Him Dead (1937)
• A Blunt Instrument (1938)
• No Wind of Blame (1939
• Envious Casca (1941)
• Penhallow (1942)
• Duplicate Death (1951)
• Detection Unlimited (1953)
• Penhallow (1942)

Some of her Regency novels also have mysteries as a part of the story but are not, strictly speaking, considered mysteries. Those are:

• Regency Buck (1935)
• The Talisman Ring (1936)
• The Corinthian (Beau Wyndham) (1942)
• The Reluctant Widow (1946)
• The Quiet Gentleman (1951)
• The Toll-Gate (1954)