Spots 
Actress Mary Blake dines with her suitor Donald Morris, haunted by an unspoken trouble that she attributes to cruel fate. Donald attempts to pledge his love and protection, but Mary abruptly flees into the night before revealing her secrets. Her dramatic sudden departure leaves Donald tormented by uncertainty about her past.
CHAPTER I
Donald Morris endures two sleepless nights after Mary Blake cuts off telephone contact and ignores his visits to her Waverly Place apartment. On Monday morning, an unstamped messenger letter arrives at his sister Helena Atterbury's home, deeply alarming Donald. He learns the message was dropped off at the Pennsylvania Station office the day prior.
CHAPTER II
Private detective Peter Clancy receives an urgent summons to Waverly Place while dreaming of trout fishing. Outside the apartment building, he encounters Officer Sullivan, who explains how Donald Morris frantically sought police assistance after finding a mysterious wispy white vapor or scarf beneath Mary's door. Clancy rushes up the stairs to investigate the locked room.
CHAPTER III
Inside the apartment, Donald Morris and Peter Clancy examine a thoroughly turned-over bedroom where bureau drawers are emptied across the floor. Clancy notices that while small accessories were dumped, fine dresses hung undisturbed, and no exterior fire escape existed near the bedroom window. A broken window pane in the kitchen suggests forced entry, yet Clancy spots subtle anomalies like a melting ice sliver in the sink.
CHAPTER IV
Peter Clancy reassures a distressed Donald Morris that the missing women planned their departure long before any apparent break-in occurred. The careful arrangement of a single protective sheet over the mattress proves the apartment was prepared for a long absence. Donald shares a poignant letter written by Mary, which reveals her intention to face danger alone and spare him from a tragic secret.
CHAPTER V → CHAPTER VI
Janitor Angelo Russo describes the two sisters living at Waverly Place, contrasting the glamorous, veiled Mary with her quieter sister Anne. Angelo notes that Anne always wore plain dark clothes and bore a prominent reddish birthmark across her cheek and neck. This stark physical detail gives Donald Morris and Peter Clancy their first solid clue for tracing Anne's movements.
CHAPTER VII
Flashing his torch along the waxed dark floor, Peter Clancy discovers dull red bloodstains leading away from the storage room. Before he and Donald Morris can process the finding, the apartment telephone rings insistently. Clancy answers, attempting to impersonate a resident, but the mysterious caller detects the deception and abruptly hangs up from a public booth at the Pennsylvania Hotel.
CHAPTER VIII
Peter Clancy and Donald Morris interview taxi driver Bill, who recalled transporting a thin, veiled woman from Waverly Place on Sunday afternoon. The woman offered a five-dollar bonus for carrying a remarkably heavy trunk down three flights of stairs without assistance. Bill caught a brief glimpse in a mirror of her face under the veil, confirming her intense expression during the secretive move.
CHAPTER IX
At Pennsylvania Station, Donald Morris falls into despair as direct traces of Mary Blake vanish, leaving only her sister's heavy trunk behind. Peter Clancy urges Donald to rest while his detective agency mobilizes to trace every taxi and railroad depot in New York. Donald describes meeting Mary through his ambitious sister, Helena Atterbury, who had coaxed Mary into a private reading despite her manager's strict protection.
CHAPTER X
Peter Clancy visits theatrical manager Frederick Jones to gather authentic photographs of Mary Blake for nationwide distribution. Partnering with Captain O'Malley, Clancy dispatches promotional portraits to investigators across the country and Canada. Later, Clancy secures signature cards at the Scoville Bank to analyze handwriting samples, systematically building a comprehensive file on Mary's personal history.
CHAPTER XI → CHAPTER XII
Detective Fox tracks a promising lead to a boarding house on Twenty-Sixth Street, where a young woman named Florence Smith paid a week in advance without luggage. The description matches Mary Blake's beauty and timid demeanor when refused a room at the Pennsylvania Hotel without luggage. Clancy insists on personally verifying her identity against the theatrical photographs before jumping to conclusions.
CHAPTER XIII
Weeks pass as Peter Clancy travels across the country, investigating false leads from St. Louis to Philadelphia in search of women with facial birthmarks. Meanwhile, Donald Morris offers a massive financial reward to stimulate information about either sister. Clancy re-interviews janitor Angelo Russo and nearby shopkeepers in Waverly Place, refining his understanding of Anne's physical strength and habits.
CHAPTER XIV
Under a sweltering, dark summer sky, Peter Clancy uses a duplicate key to slip secretly back into the Waverly Place apartment at midnight. Operating in complete silence while Rawlins keeps watch outside, Clancy flashes his torch across the darkened living room. His quiet search aims to re-examine small details that the initial police inspection overlooked.
CHAPTER XV
Peter Clancy travels by mountain train to the remote Catskill hamlet of Hobart Falls, following a fresh lead into the sisters' past. The quiet hamlet stands in stark contrast to crowded resort towns, offering a tranquil setting for untangling old family secrets. Clancy seeks photographer Walter Lord, hoping the elderly man holds vital knowledge about the Curwood family background.
CHAPTER XVI
Photographer Walter Lord shows Peter Clancy a childhood portrait of Rosamond Curwood, revealing that Rosamond and Mary Blake are the same person. Lord explains that Rosamond's sister, Anne, possessed a severe birthmark on the right side of her face. Lord purposefully photographed Anne in profile to protect her sensitive feelings, leaving a hidden disfigurement off the official record.
CHAPTER XVII → CHAPTER XVIII
Reflecting on the painful history of the Curwood family, Peter Clancy considers how much truth he should reveal to Donald Morris. Before leaving Hobart Falls, Clancy agrees to sit for a portrait in Walter Lord's dust-covered studio gallery. Surrounded by decades of local portraits covering the walls, Clancy discovers unexpected visual connections among the displayed photographs.
CHAPTER XIX
At the Hobart Falls station, Peter Clancy receives a night-letter wire warning that Mary Blake's disappearance has hit the sensational press. Learning that Donald Morris has fled to Fennimore Park with his sister, Clancy hires a local Ford automobile to drive directly across the mountains. During the bumpy ride, Clancy pieces together scraps of evidence regarding missing trunks, large bank withdrawals, and altered identities.
CHAPTER XX
Arriving at Fennimore Park, Peter Clancy reassures Donald Morris that his agency did not leak the story to reporters. While examining Mary's original letter, Clancy overhears a distinct, deep voice conversing with Helena Atterbury downstairs. Clancy instantly recognizes the speaker as Mrs. Kate Rutherford, identifying her as the mysterious caller from the Pennsylvania Hotel booth weeks earlier.
CHAPTER XXI
Confronted by Peter Clancy, Mrs. Kate Rutherford admits she called Mary Blake's apartment on May twenty-ninth after receiving a frantic farewell letter. Mrs. Rutherford reveals her deep history with the sisters, explaining how guilt and protection shaped their lives. Realizing the emotional toll on Donald Morris, Mrs. Rutherford agrees to share crucial secrets about Mary's true motives.
CHAPTER XXII
Rushing back to New York, Peter Clancy lies in wait inside the dark Waverly Place apartment at midnight. When a quiet intruder creeps down the hall with a flashlight, Clancy corners the figure at gunpoint, catching janitor Angelo Russo red-handed. Terrorized by Clancy's accusations, Angelo tearfully confesses to sneaking in to steal household valuables to pay for his sick wife's medical care.
CHAPTER XXIII → CHAPTER XXIV
Early the next morning, Peter Clancy visits the New York Public Library to examine obscure medical journals and local newspaper archives. His research leads him to Cordenham, a tiny town south of Chicago, where a specialized doctor developed experimental skin treatments. Clancy boards an express train West, confident that this medical trail will finally unlock the whereabouts of Rosamond Curwood.
CHAPTER XXV
Donald Morris returns to New York, anxious for progress, and meets Captain O'Malley at his agency office. Before Donald can leave his home, a stout landlady named Gertrude Shultze arrives, claiming she knows where Mary Blake is staying. Gertrude explains that a vulnerable, memory-lapsed woman fitting Mary's description currently resides at her Forty-First Street rooming house.
CHAPTER XXVI
Donald Morris and Captain O'Malley accompany Gertrude Shultze to the West Forty-First Street rooming house, entering unannounced to shock the resident's memory. Inside, Donald finds the frail woman who insists her name is Rosamond Curwood and fails to recognize him. Though heartbroken by her vacant stare, Donald pledges his unconditional devotion, determined to nurse her back to health.
CHAPTER XXVII → 111 West Forty —— Street
Doctor Stevens conducts an experimental setup at his sanitarium using a temporary cosmetic mark to trigger Rosamond Curwood's latent memory. Rosamond reveals she had secretly traveled to Cordenham to undergo a revolutionary ray treatment that completely erased her birthmark. Having taken her sister Anne's identity and mark to protect Rosamond's stage career, the two sisters finally unite, allowing Rosamond and Donald to embrace a joyous future.
CHAPTER XXVIII → CHAPTER XXIX
A mystery unspools across theatrical New York, untangling secret identities, hidden motives, and a sister's deep devotion.