The Highwayman Incident (Witching Well #1)

Librarian note: this is a new Kindle book cover edition for B00QL15NQ8.
Celia Quinn's business lies in ruins at the hands of Jason West, the latest in a long line of scoundrels. As she seeks to restore her family's livelihood, Celia stumbles upon lore about the local Witching Well, whose water is said to cause hysteria and psychosis. When a mysterious stranger slips Celia water from the well into her drink, she’s transported to Regency England. Her timeless adventure spans miles and centuries from modern-day New England to Merlin's Cave in Cornwall, England. Only Jason West can save her.
But Celia and Jason must tread carefully, as what happens in the past can reverberate through the ages. Their lives, hearts and futures are caught in time’s slippery hands.