Undercurrent by Michelle Griep, a review

What if, sometimes, people who go missing actually end up in another time? Michelle Griep asked herself this question and spun this story to answer it. In it, Englishwoman Dr. Cassie Larson takes some students on a short cruise in the North Sea. She buys a wooden brooch shaped like a wolf from a mysterious man. Back on the boat, the brooch falls overboard. She leans after it… and she falls too. A Viking is rowing across the North Sea, circa 900 AD.