Dylan O'Byrne, a handsome smooth talker with a beautiful Irish tenor, joins the Mill River Episcopal Church choir. He and his companion, a woman who resembles Emma's childhood friend, keep frustratingly avoiding her. With help from her techie daughter, Maggie, Emma searches the internet for clues about their identities and their purpose in Mill River. What Emma discovers leads her to believe that Dylan's companion, Mae, whom she suspects is her childhood best friend, is in danger. A pretty Texan baker, a man from Dylan's murky past in Florida, and a nerdy mathematics professor weave into this story of romance scams and lost friendship.

Emma now works as a part-time social worker at Willow Hill Nursing Home, returning to her passion for working with older adults. Gustav, a new patient, initially confounds Emma with vague references to his mysterious past. Yet, they are drawn together as Gustav subtly teaches Emma a lesson she sorely needs. Returning in Venomous in Vermont are Vickie, the kind Hospice nurse; Al and Dolores, the perfectly mismatched octogenarians; Helga, the death-sensing cat; and Detective Morris, who is mystified by how often Emma finds herself in the midst of murder.