Too Old for This by Samantha Downing

Lottie, now in her 70's, has tried to put her violent past behind her, but when producer Plum Dixon knocks on Lottie's door wanting to interview her about some murders she was accused of many years ago, Lottie murders Plum and disposes of her body. The police know Plum was at Lottie's house and are asking if she knows what happened to Plum. Will Lottie be able to stay ahead of the authorities, keep the secret of all the people she's killed and live out her retirement in peace? Only time will tell...