The Case of the Weird Sisters by Charlotte Armstrong

Three old crones plan a deadly accident for their wealthy half-brother

Alice Brennan is going to marry a millionaire. She has caught the eye of her boss, Innes Whitlock, but before they can tie the knot she must meet his sisters: three women who are so awful that no amount of money is worth enduring their company. One is blind, one is deaf, one is missing an arm, and they all want their brother dead.

The accidents begin as soon as Alice and Innes arrive at the sisters’ creaky old Michigan country house. A lamp falls from the ceiling, narrowly missing Innes’s head. When he goes for a drive, a detour sign disappears, sending him off the road and nearly killing him. Before the sisters can finish the job, Alice contacts her old history professor, MacDougal Duff, who makes his living solving murders. He is the only one who can save Alice’s millionaire from his murderous family.