The Arcanum of Beth by Mary Jane (MJ) Russell

Beth Candler's life is good. She finally realizes there is more to living than working all her waking hours as an accountant. She finds a new love, Louise Stephens, and moves into a home in the country. The death of Beth's mother brings her brother and sister-in-law back into her life. Beth has it all, and her sister-in-law wants it. Lou is only too willing to oblige. When Beth dies in a tragic accident, her best friend Janet Evans takes charge. Janet is relentless as she uses all her skills as an attorney to prove Beth's death as murder by the very women she loved. Janet risks her practice while enlisting her life partner, their friends, and the legal system to discover a truth she had rather not known - The Arcanum of Beth.