The Book of the Still is a lifeline for stranded time travellers - write your location, sign your name and be instantly rescued. When the Unnoticed learn that within the book someone has revealed both their existence and wherabouts, they are forced into murderous intercession to find it. Fitz knows where it is, but then he's the one that stole it. Carmodi, addicted to the energies trapped in frequent time travellers, also knows where it is. But she's the one that's stole Fitz. Anji, alone on a doomed planet, tries to find evidence of a race that have never had the decency to exist and doesn't know where anybody is. Embroiled in the deadly chase, the Doctor's starting to worry about how many people he can keep alive along the way.