The Secret Physics

In The Secret Physics, a dying woman’s final whisper undoes everything her son knows about their relationship, his wife, and reality itself.

Here is a longer summary:

In The Secret Physics, readers meet Jonathan Norton and Wendy Daily, a mild-mannered mortician and a beautiful linguist, married but not exactly in love. To save their grandson from an otherworldly poisoning, Jonathan races from world to world searching for Wendy and doubting his sanity. All of her family is at risk. Her parents disappeared decades before, perhaps exiled by a man who once saved her. Now Wendy journeys toward revenge and Jonathan must search for help through realities neither can understand. They must survive each other and the plot to destroy them to defend a loved one from a deadly, poisonous transformation.