Willa Noble knew it was bad luck when it was pouring rain on the day of her ever-important job interview at the Dickinson home in Amherst, Massachusetts. When she arrived late, disheveled with her skirts sodden and filthy, she'd lost all hope of being hired for the position. As the housekeeper politely told her they'd be in touch, Willa started toward the door of the stately home only to be called back by the soft but strong voice of Emily Dickinson. What begins as tenuous employment turns to friendship as the reclusive poet takes Willa under her wing.

December 1903: While Wilbur and Orville Wright's flying machine is quite literally taking off in Kitty Hawk, North Carolina, with its historic fifty-seven second flight, their sister Katharine is back home in Dayton, Ohio, running the bicycle shop, teaching Latin, and looking after the family. A Latin teacher and suffragette, Katharine is fiercely independent, intellectual, and the only Wright sibling to finish college. But at twenty-nine, she's frustrated by the gender inequality in academia and is looking for a new challenge. She never suspects it will be sleuthing . . .

Bailey King is living the sweet life as assistant chocolatier in New York City. But then her grandmother calls with news that her grandfather's heart condition has worsened. Bailey rushes to Harvest, Ohio, where her grandparents still run Swissmen Sweets, an Amish candy shop. She finds her grandfather is doing better than she feared. Unfortunately, the same can't be said for a local Englisch developer, whom Bailey finds dead in the candy shop kitchen - with Jebediah King's chocolate knife buried in his chest.

Babs Dionne, proud Franco-American, doting grandmother, and vicious crime matriarch, rules her small town of Waterville, Maine, with an iron fist. She controls the flow of drugs into Little Canada with the help of her loyal lieutenants, girlfriends since they were teenagers, and her eldest daughter, Lori, a Marine vet struggling with addiction. When a drug kingpin discovers that his numbers are down in the upper northeast, he sends a malevolent force, known only as The Man, to investigate.

In 1789 Wolfgang Amadeus Mozart visits the grave of Johann Sebastian Bach in Leipzig, looking for a sign, a signal, an answer to an enigma that has haunted him since childhood: Was Bach murdered by a famous oculist? And years later, was Handel a victim of the same doctor? Allegro follows his investigation, from the salons of London to the streets of Paris, recreating an enthralling and turbulent time, full of rogues and brilliant composers, charlatans and presumptuous nobles. Running parallel to this search is the rise of Mozart, his knowledge and fame, his trials and losses.