Nora Gilpin is introduced as a prim and proper nurse who cross paths with the renowned attorney John Raymond when he drifts through the hospital. One night, while sleepwalking, she slips into a glamorous dress and visits him at his home, behaving with a subtle, teasing allure. John, who faintly recognizes her, cannot quite place her identity, and Nora does not reveal her name. In a hurried exit, she tears her petticoat on the gate and leaves behind a small lace fragment, then returns to bed and wakes up with no memory of the events.
The next day, John becomes obsessed with finding the mysterious woman and hires a private detective to match the lace to a wearer, but the lead comes up empty. He combs the streets himself and even spots Nora in a shop with her fiancé, Tim McCarey, though Nora denies knowing him or having ever seen John during the night.
At the train station, as John is about to depart for Washington, D.C. to argue a Supreme Court case, he sees Nora again while she sleepwalks. He cancels his trip, and the two of them spend the night at an amusement park, where John spends $500 to keep the park open all night. They ride the rollercoaster repeatedly until daybreak, and in a quiet moment he realizes they had known each other long ago as children. Nora returns home and again awakens with no recollection of the nocturnal encounter.
John presses on, visiting Nora at the hospital, but she refuses any romantic connection, recognizing him only as the famous attorney. When he tries to embrace her, she slips away in anger. John is charged with assault and chooses a jury trial to force Nora onto the stand and test his account.
During the trial, Nora continues to deny a personal connection with John. He produces the lace fragment, which Nora seems to recognize, momentarily leaving her speechless. The rollercoaster operator testifies that the woman who accompanied John was not Nora, describing the other woman as having razzle-dazzle that Nora, seated in the courtroom, appears to lack. The verdict comes in: John is found guilty and fines are paid. Back home, Nora discovers that a portion of lace is indeed missing from her petticoat.
On the eve of her wedding to Tim, Nora again sleepwalks and visits John. He is determined to prove his story and proposes an immediate wedding, gathering witnesses to support him. The couple marries, but when Nora awakens in John’s room, she is horrified and bolts from the bed through an open window.
As Nora’s wedding to Tim draws near, John rushes in to stop the ceremony, and the witnesses at the house recognize Nora from the previous night, validating his tale. Nora faints, only to awaken and realize that John is indeed her husband—the man she loves. The truth settles in: their connection endured across years, and love finally breaks through the memory that sleep had hidden.
