Fleeing an East Coast life marred by tragedy, Ada Santorini takes up residence on houseboat number seven on Boat Street. She discovers a trunk left behind by Penny Wentworth, a young newlywed who lived on the boat half a century earlier. Ada longs to know her predecessor's fate, but little suspects that Penny's mysterious past and her own clouded future are destined to converge.

In a Seattle Houseboat community, the artistic spirit that has flourished since the 1950s may have ended one life, yet saved another. On Seattle's Lake Union floats Boat Street. The farthest slip on the dock holds a houseboat side with weathered cedar shingles and trailing morning glory, the white flowering vone whose loveliness is deeiving. In the 1950s, Penny, newly Mrs. Dexter Wentworth, takes up residence, dreaming fulfillment as the muse to a successful local artist destined for national renown. In present day, Ada Santorini is drawn to the same floating home, hoping itsgentle rocking will lull the pain of the personal tragedy that drove her from New York City. As Ada settle in, she discovers a trunk full of mementos of a radiant love affair that unfolded in Seattle's most iconic locales. Neighbours reveal little about the past, only that the beautiful and mysterious Penny has a hold on all who knew her. The travel writer in Ada senses the journey of a lifetime. On Boat Street, Penny's mysterious past and Ada's own clouded future are destined to converge.