Having ascertained that the purported UFO is in reality another tesseract desperate to reach Skye for help, and had not even intersected their continuum when McFarlane died, Holmes must now determine the true cause of McFarlane's death. While he does this, Skye works frantically to save another version of themselves from death, as their tesseract malfunctions, threatening to destroy not only the other continuum, but Holmes' and Skye's, as well as untold others. But the other tesseract is a slightly different design; if Skye should be within its core when disaster strikes the other continuum, she will be killed instantly. Holmes knows that each time he leaves Gibson House, his wife may not be waiting when he returns, and is mentally torn, but determinedly continues the case.

Holmes' discovery of a mysterious cave on McFarlane's property raises other issues ― if this is the reason he was killed, what did McFarlane have that was so important? As a badly run-down Skye attempts to divide her time between helping her husband and stopping the spacetime instability, she falls gravely ill, and in her delirium reverts to a childlike state.

How does Skye manage to catch a virulent form of influenza, and will her high fever permanently destroy her intellect at a crucial time? What is causing the sores on the cattle? What really caused McFarlane's radiation burns? Can the other Holmes and Chadwick fix their tesseract and restore the brane before all that they know collapses? And who killed James McFarlane?