The Hero is asked by John Sinamoi to recover a powerful truck from the hotel's parking garage. In the Hotel, Mike Davis meets the Hero at the elevator lobby and asks them to find Ken. When Ken is found, he asks for morphine. Mike Davis then tells the Hero to get to the Security room and reset the firewall to be able to proceed to the parking lot.
Once you complete this quest you will no longer be able to access any other area of the Hotel (Kitchen, Showers, Offices, Garage) except the reception. If you are trying to obtain all the collectibles make sure you do not skip any in those areas before you enter the truck.
It is possible to access the Kitchen and other areas of the hotel even after completing the mission if you die in the bar/restaurant area of the reception.