John Cullen is born in 1917 in the coastal town of Walton-on-the-Naze. As a child he is diagnosed as having catatonia, a disease which prevents him from speaking or making voluntary movements. He is, in accordance with the medical practice of the time, labelled an 'imbecile'. Aware but unable to communicate, he watches as his younger brother Robert grows up, falls in love and ultimately goes to war. In 1945, following Robert's death, Robert's girlfriend Mary starts to take John for walks along the cliff top. They pick up a watch lying on the grass, and Mary puts it on John's wrist. The watch is in fact a space/time unit (aka STU), an artificial intelligence designed to assist clients making journeys through time and space. It was marooned on the cliff-top by an unknown technical issue a long time in the future.

The watch has the capacity to cure John of his illness, enabling him to lead a normal life (although it explains that its time/space teleport functionality appears to be compromised).In 2017, John, now 100 years old and living in a care home in Frinton-on-Sea, decides that he has wearied of live. His friends and loved ones have all passed away, and he decides to bequeath the STU (which he named Vicky) to someone else . to someone who needs it. He is visited by a young mixed-race boy called Gabriel, who works for a small local newspaper as a junior reporter. John recognises someone who could perhaps benefit from Vicky. John offers Vicky to Gabriel, who understands that it is a unique gift, but even so, sees little benefit to be gained from owning a non-functioning time/space teleport device. Out of courtesy to John, Gabriel accepts the STU.

Vicky changes Gabriel's life.