Van Siller was the writing name of Hilda Van Siller (1911-82). She dropped her first name when she started out, presumably thinking that the type of books she was writing would attract more attention if readers thought the author was male. Her first novel appeared in 1943 and there was an espionage element in some of her early books. She enjoyed a long career and created a number of series characters but I have to confess that I hadn't heard of her until Xavier mentioned The Widower.
The protagonist of the story is an architect called Phillip Sargent. He's successful, but his marriage, to an attractive but disgruntled woman called Louise, is far from happy. They live in an attractive town called Bishop's corner, and Louise's irritating sister Irene lives with them, following the breakdown of her own marriage. One day, Phillip is intercepted on his way home by an attractive neighbour, Caroline Winters, who breaks the news to him that Louise has committed suicide.
A psychological tangle develops, as tongues in the town begin to wag. One review suggested that this book combines Peyton Place with a whodunit, and it's not a bad description. The portrayal of the cruelty of the gossips is very well done, as is the steady ratcheting-up of the tension. The plot is, however, rather thin. Even in a short book, which this is, I could have done with a rather twistier narrative. So it's not exactly up to Margaret Millar's standard, but few books are. I found this an enjoyable read even if I wasn't quite as impressed as Xavier, and I'm glad I followed his recommendation.