Atlantic Ocean, 1926: Voyaging from Southampton to New York, self-reliant Jane is determined to prove herself a worthy investigator on the stately ship – even awkwardly going undercover as the fashionable wife of her magnetic partner, Mr. Redvers. Few details are known about the rumored German spy the duo have been tasked with identifying among fellow passengers, but new troubles unfold once wealthy newlywed Vanessa FitzSimmons announces the sudden disappearance of her husband at sea …