The series takes place over 360 years in the future,[5][6] with most episodes set in the year 2384, in a futuristic metropolis known as Bay City.[7] In the future, a person's memories and consciousness can be decanted in a disk-shaped device called a cortical stack, which is implanted in the vertebrae at the back of the neck. These storage devices are of alien design and have been reverse engineered and mass produced. Physical human or synthetic bodies are called "sleeves" and stacks can be transferred to new bodies after death, but a person can still be killed if their stack is destroyed.