While searching the Old, Dark House or Haunted Castle for clues, the Amateur Sleuth is likely to come across one of these: a hidden room behind a wall or underneath the floor that can only be revealed by triggering an opening mechanism.
Uncovering a Secret Room often marks a turning point in the investigation since these places are always filled with evidence or compromising diaries. Alternatively, these rooms served the owner as a vault and are packed with valuables.
Video games like to feature these places as Easter Eggs, so expect to solve some puzzles before you can access these rooms. Often, particularly in platformers, a secret room may be concealed by the scenery to the players, but not to the player character.
- Kaguya-sama: Love Is War: Shuchi'in Academy's Student Council room has a room hidden behind the cabinet that Shirogane was completely unaware of until the last day of his first term as president. Karen also comes across a classic "push a certain book to move the bookcase" example during the culture festival.
- Dungeon Keeper Ami: From Research Breakthroughs:
Ami's private lab was so secret that it didn't even have an entrance and could only be reached by teleportation.
- Subverted in Coraline where Coraline finds the outlines of a little door behind a box in the living room, but she cannot open it because it's covered up by wallpaper. Then her mum rips the wallpaper open but the door turns out to be a Real Fake Door as it's all bricked up behind it, making the other side of the door impossible to get through.
- While trying to escape from the fiery blaze consuming the dining room of Castle Brunwald in Indiana Jones and the Last Crusade, Indy and his father accidentally stumble upon a communications room of the Nazis that's hidden behind the fireplace.
- The Colombian movie The Hidden Face revolves around a woman who got trapped in a secret room behind the bathroom in a designer house in the countryside. The room's entrance is Hidden in Plain Sight behind the bathroom mirror but nobody noticed it because the key to open the latch is not easy to find.
- There is a secret bunker below the actual basement in Parasite (2019). The entrance is hidden behind a set of cupboards.
- The wealthy protagonist of The Best Offer has a secret room in his house whose walls are filled with precious paintings he acquired over his lifetime. He often goes there just to enjoy the sight. The room is hidden behind a wardrobe and needs a keycode to enter. A Femme Fatal later discovers the secret room and steals all the paintings.
- Played for Laughs in Young Frankenstein. Frederick and Inga find out that there's a hidden room in the mansion, but can't figure out how to open it.
Inga: Put...ze kendel...beck!
- In Avengers: Age of Ultron, Tony (and Jarvis) scan the room Tony's in and find a secret room. Inside is the scepter of Loki that the Avengers are searching for.
Tony Stark: [To himself as he walks over to the wall] Please be a secret door, please be a secret door, please be a secret door... Yay!
- Huge plot point in The Orphanage where a family moves into a big old house. A couple of days later the son disappears without a trace which leaves his parents in despair. Only nine months later does the mother find his body in a secret basement under the stairs that was hidden behind scaffolding and a wallpaper. Apparently he was playing there and she unwittingly blocked the entrance that day which locked her son up.
- The General's Daughter: After the esteemed Elizabeth Campbell's mysterious murder, Brenner and Sunhill investigate her house. Nothing looks out of the ordinary until they find a secret room filled with bondage equipment, revealing Elizabeth's secret sex life and videotapes implicating much of the base's staff.
- Guided by Frank, Donnie Darko sets the house of public speaker Jim Cunningham on fire. The firefighters later discover a secret room in the house behind a burned-down painting where Cunningham kept child pornography material. He gets arrested the next day.
- In Daniel Pinkwater's Yobgorgle, the Rochester public library has a hidden room obscured behind a bookshelf with a special trigger to open it. The hidden room is pretty mundane, as it's just a children's reading room filled with collectible dolls, but it's the most interesting thing for a kid to do in Rochester.
- Spider's Web by Agatha Christie features one in which the protagonists hide the victim's body.
- CS Forester's short stories about Nazi Germany, The Nightmare, has a country house with a secret room. The Bower of Roses sees, first, the Jewish owner being "disposed of" by the Stormtrooper commander who appropriates the house as his own. When the Stormtroopers are in turn purged by Hitler, the new owner remembers the secret room he found and tries to take refuge there. He is later discovered and executed. Then the new owner, the Nazi Gauleiter, discovers the secret room and notes it as a possible escape route. He stocks it with what he will need to lie low for a few weeks before disappearing - should he need to. He has this need in April 1945 as the Russians close in. the Red Army officer tasked with tracking him down and arresting him is nearly taken in. Then wonders why the upstairs of the house has sixteen visible windows. But he can only count fifteen on the inside...
- In the Repairman Jack novel Legacies, there's a minor character who belongs to a group of people who like to hack buildings to find secret rooms. As skyscrapers, office buildings, and government buildings are remodeled and renovated over the years, often the crews will wall off a room that is no longer needed or doesn't fit the new layout. This group enjoys sneaking in, traveling through the ventilation system, then finding these rooms and leaving their mark or tag or calling card.
- In the Harry Potter books, the Room of Requirement is a magical room known only to those in the know. Ordinarily, it has no door, but if one paces back and forth at the right corridor visualizing something you need, a door will appear and the room will be filled with what you need. The room can be filled with anything in principle, although in practice it's mostly used for secret meetings and to hide things.
- Harry Potter and the Chamber of Secrets has the eponymous chamber built by Salazar Slytherin, located through a secret passage in the 2nd floor's girl's bathroom and only accessible to parselmouths (i.e. snake talkers). The entrance was originally just a hidden trapdoor, but because of plumbing reforms that threatened to reveal its existence, it had to be adapted into an elaborate mechanism by one of Salazar's descendants.
- The closet under the stairs where Harry lives at the Dursleys. There is very little evidence of a second child, and 2 spare rooms.
- Yours Truly: The Lovejoys find one under the stairs. The original Truly Lovejoy used it to hide runaway slaves in the days of the Underground Railroad.
- House of Anubis: In season 2, the students discover a secret antechamber in the cellar, which not even Victor or the teachers knew existed. This antechamber leads to a series of trap-filled tunnels guarding an important treasure, but the antechamber is treated as a separate place in-and-of-itself, a secret study room for Frobisher-Smythe.
- Michael from Arrested Development discovers the model home has a secret room under the stairs in the episode "Faking It". It also turns out Tobias knew about it for a while and has been storing bodybuilding magazines there. Michael later realizes that the houses his father was building in Iraq should have a secret room as well since they're based on the model home. He checks and finds evidence that proves his father was innocent of treason.
- The premise of Geraldo Rivera's much-hyped Al Capone's Vault television special was that he would break into a hidden room - the vault of legendary gangster Al Capone - on live television. Over the course of the two-hour event, the viewers were led to believe the vault was full of the gangster's loot, evidence of dastardly crimes, and/or moonshine. Instead, viewers were disappointed to discover the vault was empty with the exception of a few dusty bottles.
- In The Suite Life of Zack and Cody episode "Arwinstein", Zack and Cody stumble upon a secret laboratory in the hotel, where Arwin created and then hid away his monstrous robot. When the twins ask about it, he attempts to deny that the room even exists.
- In The Flash, S.T.A.R. Labs features a hidden room known as the Time Vault, built by Eobard Thawne while disguised as Harrison Wells, which he uses to keep his more shady activities such as the Reverse-Flash suit and his AI Gideon.
- The Doctor Who episode "Pyramids of Mars" has The Doctor and Sarah Jane hide in a priest hole.
- Vampire: The Requiem: Characters can add hidden chambers to their Home Base by investing in the Point Build System's "Tomb" Merit. They can only be found with careful investigation and can be sealed against intruders for extra protection, but, once breached, their Security bonus is permanently nullified.
- There are at least two secret rooms to be found in The Painscreek Killings. One in a study room behind a bookcase and one that can be entered via the backside of a closet.
- Safe Cracker has a few of these. Then again, the blueprints for the house are in the foyer, so an observant player can discover them quickly. Getting inside is the real puzzle.
- Professor Layton and the Curious Village: The mansion has a secret room filled with the family fortune.
- A Hat in Time: The spaceship has a secret room where Hat Kid puts her diary.
- Paper Mario: Mario's house has a secret basement where you can find Luigi's diary.
- In King's Quest III: To Heir Is Human, Manannan's study has a Secret Underground Passage that serves as the only way to access his laboratory beneath his manor which contains his spellbook and various magical ingredients. The lever that reveals the stairs beneath the study's floor is hidden in the bookshelf.
- Nikifor's house in the second Aura game has one, containing the dead body of the house's original owner, and its self-destruct system. It's hidden behind a Bookcase Passage, which needs to be powered up to open.
- Secret rooms are a staple of the Myst series, from Sirrus and Achenar's hidden stashes in the first game, to Gehn's secret control rooms in Riven.
- Maniac Mansion has a kind-of example. The room wasn't meant to be hidden. It's just that the door was painted over so many times that it now blends into the wall. However, the player can't find the door without using paint thinner.
- Buildings in the Dishonored game series have a bunch of secret rooms for the player to discover. Usually, they are filled with valuables and bone charmes like this room hidden behind a fireplace.
- In the house for Burglary in Dishonored, there is a secret room in the bedroom that is covered with pictures of Lady Boyle.
- Right at the start of Dishonored 2, you have to find the Imperial Safe Room which is located behind bookshelves off the Imperial Chambers. To access the room you need to fetch one of the Imperial Signet Rings from an enemy. Doubles as a Secret Passage as the door at the other end leads you into the city.
- PAYDAY The Heist has a hidden vault inside the First World Bank, which can only be uncovered by four people (in the players' case, robbers) standing on hidden pressure plates in specific spots in the chamber leading to the bank's main vault. Successfully triggering all four plates at once opens up a false wall hidden in the back of the bank, revealing the vault door.
- PAYDAY 2:
- The climax of the Framing Frame job tasks players with stealthily locating and infiltrating a hidden vault room (that's always hidden behind a bookshelf) that's filled with the spoils of an illicit arms deal in the condo of an American senator, stealing the gold within for themselves and replacing it with less valuable cocaine to frame him. Though if they are detected, they're forced to leave the gold behind and simply leak the arms deal to the press to keep their benefactor happy, missing out on most of the job's potential profit.
- In addition to keeping the aforementioned secret vault intact in the remake of that level, unlocking the game's True Ending requires finding a secret passage that leads to another hidden vault in the White House heist, which is hidden behind a painting only that can only be moved after fulfilling a number of convoluted hidden requirements in other parts of the game, and successfully opening it (requiring, among other things, translating ancient Sumerian).
- RuneScape: The haunted mansion where the "Broken Home" quest takes place has three rooms, each hidden behind false walls or hidden trapdoors and requiring triggering hidden switches to activate, often requiring items from a different part of the mansion (one is triggered by fixing a piano by inserting a missing piano key then playing the piano revealing a chamber where a lot of the staff's corpses were hidden when the house became haunted, one is triggered by removing the head of a bust to find a hidden button revealing a room where one unfortunate servant was trapped inside until he starved to death, and one is revealed by replacing a statue's missing crystal eyes revealing a Shrine to the Fallen to the son of the mansion's former owner before he went mad.
- In Close to the Sun, Rose has to solve a puzzle to find the entrance to the secret room in her sister Ada's apartment where an important notebook is stored.
- Classic Infocom game Deadline features one of these where the updated will is hidden.
- Ace Attorney
- During the events of "The Rite of Turnabout" in Phoenix Wright: Ace Attorney Spirit of Justice, Phoenix Wright discovers a hideout for the La Résistance hidden behind a statue that was part of a ritual ground sacred to the Kingdom of Khura'in. The fact that the hideout is secretly accessed through a religious site implicates a local priest and his wife as part of the rebels against the Kingdom.
- During the events of "The Forgotten Turnabout" in the sequel to Ace Attorney Investigations: Miles Edgeworth, Edgeworth discovers a secret floor between the 50th floor and the roof of the Grand Tower. The secret floor was used to store evidence which was stolen from police custody and set to be auctioned off to the highest bidder.
- Last Window: There is a secret room hidden between floors accessible via a hidden hatch in the elevator.
- In Havenfall Is for Lovers, a secret room in the heroine's house is filled wall to wall with weapons. Across multiple routes, the heroine's discovery of the room prompts the realization that her parents kept secrets.
- These abound in Scooby-Doo, and are usually found accidentally by "Danger-Prone Daphne".
- Subverted in an episode of Little Princess. The Princess discovers a room in the castle which nobody uses and thinks it's a secret one only she knows about, but it turns out that everybody knows about it, they just don't use it because they see it as useless.
- In The Simpsons, the house of the Simpsons' neighbors the Flanders has a secret room with merchandise related to The Beatles.
- Played With in "Treehouse of Horror IV". Bart and Lisa search for a hidden room in Vampire Burns' castle, but it turns out the "secret room" is pointed out with blatantly obvious signs. Unfortunately, this proves to be Schmuck Bait, as it leads the kids to wake up the vampires within and Bart being bitten (after he falls for another piece of Schmuck Bait by pulling the "Super Happy Fun Slide" lever).
- Gravity Falls: The Mystery shack has a fair number of them. These include the wax figure storage room (door wallpapered over), the room with the Body Swap rug (door hidden behind a non-revolving bookcase) and the many rooms in the basement (path hidden behind a vending machine).
- In Star vs. the Forces of Evil, there are a number of secret passageways and rooms in Butterfly Castle. While Star and Moon are aware of some of them, only Eclipsa knows all of them.
- In the Family Guy episode "And Then There Were Fewer", the guests are searching the dining room where James Woods was murdered for clues. Someone leans on a bookshelf, which opens to reveal a hidden chamber... that turns out to be the laundry room. Further searching turns up another hidden room full of actual clues.
- Chip 'n Dale Rescue Rangers episode "Pound of the Baskervilles" has the intrepid rodents go snooping through Baskerville Hall in search of mystery writer Howard Bask's last will. As Chip is an avid fan of Bask's stories, he's able to deduce clues about various hidden latches in the manor house that ultimately lead to a secret workroom where Bask penned most of his stories. It is in this room that the will found.
- During World War 2, many people fleeing the Holocaust unable to flee Europe before the blitz took shelter in rooms hidden behind furniture like bookcases and cabinets.
- Corrie ten Boom's autobiography, The Hiding Place, describes how her family hid a number of Jewish friends in their home, the Beje. Ultimately they built a secret room for them to use in case of a raid, while the ten Booms provided food and other necessities for them.
- Many stops on the Underground Railroad had secret rooms to hide the escaped slaves.
- Priest Holes were secret areas in large houses where English Catholics could hide priests, who were accused of treason against the English crown at the time.