Though I Know She Lies (1965) is a solid mystery novel by Sara Woods, and is one of the nearly 50 "Antony Maitland" mysteries that she wrote in her 25 year career.
Antony Maitland is an English barrister who often works alongside his Uncle, Sir Nicholas -- who is also a barrister, although a much more orthodox one than his creative and hunch-filled nephew. Antony is called in by his uncle to do a little investigating on his case defending a beautiful woman who has been accused of murdering her sister. The case has just gone to trial, so there isn't much time, and Antony soon finds himself tied in knots around a series of witnesses who are all obviously lying, but about different things and for different reasons. And although Antony and the rest of the defense want to believe that their captivating client is innocent, they all suspect that they may just be duped by her beauty into wanting her to go free.
This is an engaging mystery with fun twists, turns, and red herrings, and a satisfying ending. If you like mystery novels, then I don't see how you could go wrong with Antony Maitland and his crotchety uncle.