(Takashi Oda's universe)
Lost is the second chapter of The House of the Dead 4.
In a flashback several days earlier, AMS agents James Taylor and Kate Green enter the Classified Documents Room in the agency's European branch office. James suspects that the events from an incident three years prior, which he helped neutralize, haven't ended. An earthquake rumbles the building and traps them inside.
Back in the present, James and Kate fight through the sewers to a construction area for the branch office's expansion, hoping to reach the surface from there. When the pair enter the Classified Information Room for any evidence relating to the incident, they discover a plot to launch nuclear missiles, confirming James' suspicions.
The agents hurry to a construction elevator, but are forced to jump off when the Lovers, a small male spider connected to a larger female, grab the lift. After being defeated, the Lovers fall into the dark elevator shaft to their deaths.
Upon starting the chapter you will be attacked by several Ebitans. They're simple creatures that are covered in sewage and attack by lunging at the player. After clearing them out you will turn around, where more creatures are pursuing you. The creatures are too far to hurt you, but it doesn't hurt to gain some points so clear some out before you turn back. Your characters automatically move forward and will look to the left where three Damiens will attack. A crate behind them can be destroyed for a points-reward item. As you reach a door, more Ebitans will pop out from the water and attack. After they are dealt with, the pair look to the left and see more creatures after them. A message will appear to shake the gun to open the door. If you don't open the door in time, the group you just looked at will need to be dealt with. However, if you do open the door in time, you can ignore the group you just looked at and go straight to the ladder.
If that group is fought, after they are defeated you will take a detour where four more Ebitans will appear. Clear them out and you will move to the side where two more Damiens will attack. Afterwards, a rusty barricade will collapse and release a good amount of creatures to deal with before you head for a developed part of the sewer. Throw a grenade in the alcove; this unlocks a secret area once the appearing creatures are killed. More Ebitans and two Damiens will appear and once those are dealt with, you will automatically proceed to the next area. If you threw a proper grenade into the alcove, you will find a secret area containing several point-boosting items before going back to the main path.
After climbing up the ladder, several Murrers will pop out of a small vent. They are not that durable and can be killed with a single bullet, but come in enough numbers to worry the players. After being dealt with, you will pick between two paths.
- Sewer Path (Left): If this path is chosen, two Ebitans will attack from a doorway to the left before you will climb down. More creatures attack after reaching the ground, including eight Ebitans. Once dealt with, you will move to the side where two Charles creatures will attempt to throw barrels at you. Afterwards, a large group will appear from the side as you proceed before you will move further in.
- Pipe Path (Right): If this path is chosen, several creatures will appear from an opening in front of you and attack. You will automatically proceed further until four more Ebitans crawl up onto the pipe. Once those are killed, James will tell Kate to watch her back, and more creatures including two Charles, one carrying a barrel, will attack. Once dealt with, you will proceed further in when you look to the left and two more Charles will be seen attempting to throw barrels at you. They can be killed normally or you can shoot the explosive barrel to kill both of them at once. There's a green barrel near the explosive one that contains a life booster. After the two Charles are disposed, you will climb down onto the pipe where two Damiens will appear from the small ventilation shaft, and after those are dealt with several Ebitans will attack from behind. You will climb down the crates when a few more creatures will attack. After that group is disposed of, four Ebitans will attack from the water. Once those are killed, another group of Murrers must be destroyed before you climb up a ladder.
After climbing up the ladder, more creatures appear from the doorway. Clear them out before moving into a storage area where a cutscene will occur and several creatures break free of a barricade. Clear them out and proceed further where another group of Murrers will attack. There is also a lock next to them which can be shot; this will open a new path. Once the Murrers are destroyed, two Berns will burst out of another container and attack.
If you destroyed the lock, you will proceed into the new path and a life booster can be shot at. When you leave the container, a Charles will shove you immediately after it sees you. You will navigate through the path when two more Berns will appear. After those are dealt with, you will find three Charles carrying barrels; two of them will attempt to throw them while another will get up close. Kill the ones throwing the barrels first. After they're killed, proceed into a room where a large number of creatures are waiting for you. An explosive barrel is near most of them and can be shot at to destroy most of the group. As you try to reach the Classified Information Room, a creature will attempt to grab your leg; shake it off and clear out any remaining enemies.
After the cutscene, you will leave the Classified Information Room and find several creatures attacking you. If you can, clear out the Charles attempting to hold the shutter to block some of the creatures. After those are dead, you will find a construction area where a lift will drop off three Berns and Ebitans; only one Bern will attack at first, but the more Ebitans you kill the other ones will begin to join the fight. Try to kill the other two Berns first as they won't do anything until attacked. After the group is cleared, you will proceed to a lift, where two more Berns and four Ebitans will attack. Clear them out then get on the lift.
As you enter the lift, a moment of peace occurs when suddenly the lift stops. You will see two spider legs are holding onto the lift, so open the door and you will jump to the next one. The Lovers fight will begin after jumping to the next lift. After killing the Lovers, this chapter is complete.
- Main article: The Lovers#Gameplay