Quick answer: Take the Tongue from the Red Serpent House (Crimson Forest) and the Fang from the Black Serpent House (Village of Lu), then use the Loong Emblem to open the White Serpent House on Meigu Lake for the Eye.
What The Four Serpent Houses asks
The Four Serpent Houses is a story quest in Phantom Blade Zero, and it sits alongside the rest of the game’s quests and side quests. Its first objective reads “Find the Serpent Eye, Tongue, and Fang”. A second objective follows: “Use the Loong Emblem to unlock the White Serpent House”.
At the Green Serpent House in the Pangzhen backstreet, interact with the serpent statue to insert the three pieces. It offers a separate option for each one:
- “Insert the Serpent Eye”
- “Insert the Serpent Tongue”
- “Insert the Serpent Fang”
Once all three are in place, a hidden passage opens. That passage is how The Heart’s Trail moves forward, the quest that starts at the end of Town of Death. Its objective, “Enter the Mirage Estate through the hidden passage in the Green Serpent House”, is completed at the same statue.
If you examine the statue before collecting anything, it points you elsewhere. The golden Eye is hidden in another of the Order’s Serpent Houses, and the missing Tongue is kept in a different Serpent House as well. There are four houses in total, each with a bell that shares its name:
- Red Serpent House, Crimson Forest
- Black Serpent House, Village of Lu map
- White Serpent House, Meigu Lake
- Green Serpent House, Pangzhen backstreet
The Order: The Four Serpent Houses letter
A book named The Order: The Four Serpent Houses lies on the candlelit altar on the upper floor of the Green Serpent House. The upper floor has no way in from the bell side. Go round the house to the yard on its far side, where three big-headed doll enemies stand guard, then climb the stone steps up to the terrace behind the house, take the short stair onto the roof and walk in through the opening into the upper floor.
The letter is a short guide to the Order’s four houses and where each one stands:
- “Green Serpent House, located in the back streets of Pangzhen, specializes in reproducing many secret medicines of the Wulin.”
- “Red Serpent House, north of the long bridge in Crimson Forest, is dedicated to studying the fusion of medicine and Esoteric Arts.”
- “Black Serpent House, in the western corner of the Village of Lu, specializes in antidotes.”
- “White Serpent House, on an island in eastern Meigu Lake, has stopped dispensing medicine.”
The same floor holds Serpent Gall: Green, one of the four pieces that make Serpent’s Memory for White Serpent & Crimson Viper.
Red Serpent House: Red Serpent Tongue and Loong Emblem (yin)
Start at the Red Serpent House bell in the Crimson Forest. The Red Serpent Tongue is a pickup about 40 metres from that bell, and its pin is marked on the Crimson Forest interactive map. Its item card reads:
A mechanical serpent’s tongue. Cold, lifelike, and exquisitely crafted. The mechanism at its base seems made to fit a hidden keyhole.
This token was carefully placed within the Red Serpent Manor. What secret might it unlock?
A second pickup, the Loong Emblem (yin), lies about 11 metres from the Tongue, which also puts it about 40 metres from the bell. Its card reads:
A Loong with its head bowed, its finely detailed scales almost lifelike. Its eyes, inlaid with black jade, glow faintly in the darkness.
A smooth, rounded notch along its left edge appears to fit together with another fragment.
Black Serpent House: Black Serpent Fang and Loong Emblem (yang)
Find the Black Serpent House on the Village of Lu interactive map. The Black Serpent Fang is a pickup roughly 50 metres from the Black Serpent House bell. Its card reads:
A serpent’s fang finely carved from crystal, smooth as a mirror and sharp as a blade. The slightest carelessness could see it pierce anyone seeking its secrets.
Yet there are always those willing to brave this risk, if only to glimpse the truth beyond the door.
The Loong Emblem (yang) sits about 11 metres from the Fang and about 50 metres from the same bell. Its card reads:
A Loong with its head raised toward the heavens, its whiskers flowing gracefully. Its eyes, inlaid with agate, gleam as though alive.
A smooth, rounded notch along its right edge appears to fit together with another fragment.
The Red and Black Serpent Houses can be done in either order.
The Loong Emblem: Joining the yin and yang halves
Once you hold both halves, they combine into the Loong Emblem by themselves. Nobody needs to forge it for you. The finished emblem’s card reads:
An emblem pieced together into a whole. Upon it, one Loong coils while another rises proudly, both weaving among billowing clouds, the sun and the moon.
It seems capable of opening a Loong-shaped lock somewhere.
White Serpent House: White Serpent Eye
At Meigu Lake, the White Serpent House is secured by a lock shaped like a Loong. Use the Loong Emblem to open it and complete the objective “Use the Loong Emblem to unlock the White Serpent House”.
The White Serpent Eye is inside, roughly 60 metres from the bell for White Serpent House, as marked on the Meigu Lake interactive map. Its card reads:
An amber crystal shaped like the eye of a serpent. Within its translucent core is a naturally embedded dark band, shimmering and shifting with the angle of the light, as if the serpent’s gaze were following your every move.
Green Serpent House statue: Opening the hidden passage
Serpent pieces and Loong Emblem locations
| Piece | Serpent house | Region | Nearest bell |
|---|---|---|---|
 Red Serpent Tongue | Red Serpent House | Crimson Forest | Red Serpent House, about 40 m |
 Loong Emblem (yin) | Red Serpent House | Crimson Forest | Red Serpent House, about 40 m |
 Black Serpent Fang | Black Serpent House | Village of Lu map | Black Serpent House, about 50 m |
 Loong Emblem (yang) | Black Serpent House | Village of Lu map | Black Serpent House, about 50 m |
 White Serpent Eye | White Serpent House | Meigu Lake | White Serpent House, about 60 m (needs the Loong Emblem) |
