When a mistress learns her lover has died and his death erroneously ruled a suicide, she must untangle the true cause of his death.

Seedling of idea here. So probative questions will help me workshop this. Thinking mistress actually did it but she has some psychologist issue hence word “untangle” here. (And think that should haven been ending of a certain HBO show by the way.) I want her to seem like truly sympathetic protagonist until twist.