Ferdinand wakes his sisters after midnight and leads them to the hidden door behind Julia's tapestry. Bolts draw back, but a rusted lock still blocks entry; while they stand frustrated in the dark, footsteps echo from the other side and prove the southern buildings are occupied by something other than wind. The siblings retreat, shaken less by superstition than by confirmation that the marquis has lied. On a later night Ferdinand cuts the lock and opens decaying galleries, ruined chapels, and a south tower stair that crumbles under his weight. He spends more than an hour trapped above a chasm in darkness until Madame and his sisters search the passages and rescue him at dawn.
Between explorations, romance and politics tighten around Julia. Hippolitus finds her singing at the seashore at evening, declares his love while she plays her lute, and is interrupted by the jealous marchioness. Ferdinand later convinces the count in an adjoining room that Julia returns his passion, recounting her melancholy during his absence and the spill of wine when his departure was mentioned at table. Julia overhears from the closet, is discovered, and flees ashamed yet happy. A second midnight search sends Ferdinand through a black marble hall where sullen groans rise from beneath the flags and every barred door refuses entry. Emilia and Julia beg to change apartments; the marchioness ridicules superstition and refuses because her pleasure rooms are being prepared.
Ferdinand reports the disturbances and is summoned to swear on his father's sword before hearing the marquis's confession. A century earlier his grandfather murdered a della Campo enemy in the southern buildings, and the marquis himself once witnessed horrors there that made him seal the wing forever. Ferdinand must vow eternal silence while inheriting blood guilt he did not commit. He grows reserved with Hippolitus, horrified to learn what the castle conceals.
The marquis then informs Julia she will marry Duke de Luovo. She kneels, pleads that her heart cannot follow her hand, and is threatened with exile. Summoned to receive the duke in splendor, she gathers desperate composure and appeals to his generosity, confessing honestly that affection is already given elsewhere. He treats the confession as insult, confirms the engagement with her father, and leaves her dreading the marquis's rage. Nuptials are fixed for three days, then accelerated after the wounded duke's pride.
Hippolitus, well enough to conspire despite his earlier wound, meets Ferdinand at midnight to negotiate Robert's keys while Julia waits through hours that feel like ages. The marchioness directs magnificent wedding preparations downstairs, unaware the bride is packing for exile. Robert yields the keys after apparent sympathy; Ferdinand and Hippolitus are delayed past midnight by household noise that may mean they are watched. At one o'clock they move Julia through rusted locks, a key that breaks in the lock, and mistaken passages while pursuers roar behind doors. Julia clings to Ferdinand in the dark, believing capture certain, until pursuit noise suddenly ceases when the marquis's men take the wrong route. That mistake allows escape to the woods at grey dawn, where the marquis ambushes them at the private gate he always knew they would use; Robert's cooperation was permitted only to complete the trap.
He stabs Hippolitus before Julia's eyes, seizes Ferdinand for the dungeon, and imprisons Julia to be marched to the chapel as a sacrifice to the duke. Hippolitus's men carry his bleeding body to a waiting boat for Italy. Julia awakens a prisoner, forbidden even Emilia's comfort, and learns the wedding will proceed in forty-eight hours.
Ferdinand understands from his cell that Robert's apparent sympathy was a trap: the marquis knew the private gate would be used and let the keys change hands only to complete it. His caution at the inner doors, waiting until one o'clock for household silence, gave the watchers time to position servants at the escape route. Julia spends her confinement hearing feast preparations while the marchioness directs the alliance she helped force, fanning the marquis's revenge hotter than ambition alone would burn. Emilia, denied access to her sister, can only guess at the cruelty unfolding upstairs.
By the chapter's close Julia has lost lover, brother, and liberty in one scene that turns Gothic mystery into patriarchal violence made visible. The hidden passages have answered whether the southern wing is haunted and replaced that question with a worse one: who still lives behind the stones, and how long the marquis can keep blood and marriage on the same ledger. Ferdinand hears from his cell that Hippolitus may yet breathe, but Julia is told only that the chapel awaits her in two days. Emilia, denied her sister's presence, can do nothing but wait for the ceremony that will trade one prison for another. The chapter ends with coercion visible and rescue still uncertain.
