At age 77, Marylou Ahearn is a woman on a mission. With nothing to lose but money and much to gain in satisfaction, she heads for Florida to murder the man whom she holds responsible for the death of her daughter.

Marylou has Googled Dr. Wilson Spriggs, the scientist who in the 1950s headed up an illegal radiation experiment on pregnant women, one of whom was her, and traced him to Tallahassee. In this darkly funny novel, she plots to track him down, dispatch him swiftly and face whatever consequences await her.  He killed her daughter, who died of cancer at age eight, just as surely as if he'd shot her. Although the class action case was settled through the courts, financial compensation is not enough. Marylou believes that Dr. Spriggs needs to pay personally for his sins.

She hasn't yet decided how to do the deed. In fact, she's not sure she'd recognize him after all these years, but the old man who putters around in the yard of a house down the street bears his name and fits the description. As she strikes up an acquaintance with him, she soon realizes that he is definitely the right guy, but he can't remember what he had for breakfast, let alone recall or feel remorse for the calamity that he caused half a century ago.

While she mulls her choices to do him in, Marylou begins a campaign to finagle her way into the senile old man's family.  She plies him with homemade muffins. Poison, perhaps? She takes him on walks. Lose him in the woods? An accidental fall? As she reads the newspaper to him every morning and helps him work the crossword puzzles, she learns more about his family. The mother is self-absorbed in the throes of menopausal meltdown, and the stepdad is so glued to his computer, obsessing over hurricane tracking, that they largely ignore their three teenaged children. The two elder teens, both being treated for Asperger's syndrome, have stretched their parents' patience wafer thin. When Marylou learns that they are unable to drive because of their medications, she offers her services as chauffeur. She gets to know the family through Beth, the youngest and only relatively normal member of the household who has injured a knee while in training for summer sports camp. Beth is sidelined and bored, and Marylou takes her under her wing.

She learns that the eldest child, Otis, spends every waking moment tinkering with smelly chemicals in a backyard shed. He turns to his physicist grandfather, who oddly still remembers nuclear physics formulas, but fails to recognize that his grandson's questions range well beyond idle curiosity and that he is constructing a radon gun. She also finds out that the beautiful Ava, currently obsessed with Elvis Presley, secretly yearns for a modeling career.

This is when Marylou hits on the perfect crime. Instead of killing the old geezer, she'll wreck his family from within, just as he ruined her family long ago. She embarks on a diabolical scheme to give each of the children exactly what they want. She aids and abets Otis's search for radioactive materials, and pays for a professional photo shoot for Ava that includes nude shots that end up on the Internet. It's when she involves the bored and injured Beth in a cultish church that things begin to go seriously wrong for the entire family.  Just when her scheme to destroy the family seems to be working, she realizes that she cares about them and that they care about her.

THE REVENGE OF THE RADIOACTIVE LADY takes some quirky, darkly humorous twists and turns as Marylou discovers what she really wants from life.