The year is 2001 and astronauts Dave Bowman (Keir Dullea) and Frank Poole (Gary Lockwood) are dispatched to deep space on a mission to Jupiter inside the mighty Discovery space vessel. The ship is run by one of the units from the state-of-the-art HAL 9000 computer line. In truth, the computer aboard the ship is not just a machine but has been adopted as one of the crew, which includes three more scientists making the journey in cryostasis. "HAL," as the crew calls him, speaks with a calm, steady voice (from actor Douglas Rain) and even "mimics" human personality. The mission does have its quirks, one of them being the rumors surrounding the reason for its inception. Some say that something strange was dug up under the surface of the moon. Dave can't say for sure why he's out there, other than to follow orders. However, things get even more strange on the ship when HAL alerts the crew to a malfunctioning communications device. In a thrilling space walk, Dave replaces the device, only to find it in perfect condition. HAL cannot account for this mistake, and if it is an error, it would be the first recorded mistake ever made by this line of supercomputers. In a classic scene, Dave and Frank sit in a sound proof pod and discuss their concerns about the mission. Frank is very much afraid that HAL is defective and will have to be disconnected, thereby putting the mission in jeopardy. Dave isn't sure what to do, but knows Frank may be right. Outside the pod, HAL watches, but unbeknownst to the astronauts, it can read their lips and knows everything they are saying. The decision is made to replace the "defective" device to see if it fails. Frank makes the space walk this time, and in a sudden tragic turn of events, his pod rushes at him, driving him into deep space. Frank's oxygen supply is cut in the process. From inside Discovery, Dave watches in horror as his friend suffocates in space. Dave takes another pod out to recover Frank's body. During this time, HAL silently cuts the life support from the cryostasis pods holding the rest of the crew. As alarms sound inside the empty spaceship, the three defenseless scientists die quickly. When Dave returns to the ship, he asks HAL to open the pod bay doors. "I'm afraid I can't do that, Dave." HAL explains it will not allow Dave to jeopardize the mission because of a mistake it made. Dave ultimately finds a way back into Discovery, however, and makes for HAL's memory banks. He begins to disconnect HAL's higher functions and, during the process, HAL literally loses its mind. It slowly descends into oblivion until it is completely offline. HAL is one of the creepiest characters ever to be found in deep space. The soft, unwavering delivery of HAL's voice is far more frightening when you see how it deliberately puts its human crewmates in danger and/or kills them. HAL is devoted to the mission, but the reason for his error is still mysterious and fascinating. For all of HAL's power, however, it had no physical form with which to stop Dave from shutting him down. It's all too similar to the way HAL struck at his sleeping crewmates in stasis, who were unable to fight back. At least for HAL, he deserved what he got.