I have yet to read The Bridesmaid but when I do I'll add my thoughts - here is a plot summary from http://www.jandysbooks.com/; they have given this book 3 stars.
Philip, his sisters Fiona and Sarah and mother all live together in a smallish flat in London after his father died. Fee is getting married, Sarah is acting strangely, and his mother is a dependent woman who cannot exist without a man around.
At the wedding, Philip falls for one of the bridesmaids. Senta is the groom's cousin. Philip is immediately enthralled. While Fee is away on her honeymoon and his mother and other sister are taking a vacation, he and Senta get extremely close extremely quickly. Only when it is too late does he realize that this relationship requires more than a normal one to keep it steady. Senta's idea of proof of undying love is rather skewed. By the time Philip is able to sort out Senta's lies from the truth, he is in a situation that he cannot fathom.
This is the second novel I have read by Rendell. It will probably be the last. This is one where the writing is good but I don't like the story. I had to stay with the book, find out what happens to the players. But I didn't care for them. I've discovered I don't like Rendell's personality twists in her characters.
Notice: Strong sexual content
The Bridemaid was also made into a movie in 2004 - Film4's review: http://www.film4.com/reviews/2004/the-bridesmaid
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