|This is a chapter article.|
This page covers a single section of the game. For the full plot overview, see the game's associated storyline page.
- For the story information, see the Half-Life storyline article.
The chapter takes place in a large flooded underground industrial area infested with aquatic alien creatures. At the beginning of the chapter, the Rail Cart goes off the tracks, and crashes into an abandoned silo. The next area is a large room with a pool in the center. The player enters to see an Ichthyosaur jumping out of the water and killing a scientist. The scientist in the observation room was told that the creature was hauled from the Challenger Deep. He suggests the player to use the tranquilizer gun in the shark cage to kill the creature.
There is a scientist in a room near the generator area. He unlocks the door when the player kills all the creatures nearby, and warns the player about the next area. Inside is a cryogenic storage area with large tanks. Eventually, the player comes across a security guard with an urgent message to deliver to the player, but he gets killed by the Black Ops assassins in mid-sentence. The player is ambushed and captured by the Marines in the following area. They throw the unconscious player into a trash compactor, but the player wakes up and escapes before he gets crushed.
 Other versions
 Half-Life expansions
In Blue Shift, Gordon is seen dragged by the Marines from Barney Calhoun's perspective in the chapter Deliverance. A cut mission in Decay involved the rescue of Gordon from the trash compactor. The original level was also updated to reflect the changes done for the mission in the PlayStation 2 version.
 Behind the scenes
The original chapter title was Abandoned Silo. The abandoned silo is actually the early version of the silo from the chapter Blast Pit. The cut alien enemy Archer was to appear in the flooded hallways in the map c2a3. They were replaced with Leeches in the final version of the game. There is an unused trigger for the track Nuclear Mission Jam in the map c2a3. The track plays on map load in the Source version of the game. This is most likely an oversight. The map c2a3c uses "dawn" texture set for the skybox, even though the sky is not visible anywhere in the map. The set itself is not included in the game, but it can be found in Day One's files.
Animations for the ambush scene were created but left unused. This sequence shows Gordon being captured by the military from the view of a security camera, a leftover from when third person cutscenes were still planned for the game. The animations can also be found in Day One's files.
 Associated media
- Additional images related to Apprehension
- Half-Life soundtrack, Apprehensive Short
- Half-Life soundtrack, Bass String Short
- Half-Life soundtrack, Scared Confusion Short