P-Body wakes up to find himself rebuilt in Trinus Labs. Since he arrived, GLaDOS has found old parts of the facility and is merging the two together. However, goo is rising, and if GLaDOS doesn't realize soon, P-Body needs to take over and escape.
A demo of the first level. WARNING: The level doesn't close itself (because it thinks it needs to go to a different level), so once done, just exit via the menu.