An alien object is discovered off the coast of California; a sphere that transports people to other solar systems. Death-row inmate Russell Harris and nine other convicts are given the chance to save their own lives by agreeing to travel as test subjects on the transporter. But when the first volunteer dies a gruesome death, it becomes clear to Russell and his comrades that the venture is little more than a merciless death mission on which they will all perish. Their only chance of survival is to uncover the secret of the mysterious object, but that too seems hopeless – because no trace of the transporter’s constructors can be found.