The narrator of "The Tunnel" has run away with his young girlfriend -- they are fugitives from parents who would not let them see each other because of their different social status. The two live on the third floor of an abandoned tenement block that is due for demolition. Although the conditions are horrible and money tight, Clancy and the narrator don't seem to mind for they are in love. The story becomes one of betrayed ideals as the characters' young love falls apart after the passion wears thin. This is the case until a tunnel dug by schoolchildren in a vacant school lot gives the narrator new hope.
"The Tunnel" employs one of Swift's favorite messages, that children are the future. This is portrayed through both the two young lovers acting out adult lives until they realize that it is much better to be children and by the schoolchildren digging in the abandoned school. Both of these themes become very important in Waterland. By digging a tunnel under the wall, and then crawling from the school yard into the public park, the children are effectively "escaping" one of society's primary institutions for training children to be "proper" adults.
Many of the other images portrayed in "The Tunnel" are familiar from Swift's other works. For instance, the narrator describes some abandoned "shop-window dummies, their arms and legs sticking up like some vision from Auschwitz." (p.81) Images of World War II appear again and again throughout the short stories, and are prevalent in Out of This World and Waterland.
Although the couple is very much in love at the beginning of the tale the excitement of sex quickly wears off as money wears thin and they begin to feud. Forced to go out into the adult world and find work, the situation grew desperate. At just the point where the atmosphere in the flat seems unbearable the narrator scalds his arms with boiling water. The resulting injuries rob him of his adult capabilities reducing him to a completely childlike state of dependency on Clancy. As long as the narrator needs Clancy to care for him, the situation between them improves.
While an invalid the narrator watches several children playing in the abandoned school that lies outside his window. When the boys discover that they can break into the school their first instinct is to ransack everything they can find. This pointless rebellion is a natural first reaction of the child in Swift's writing to the oppressive system created by the adult world. After some time the kids give up their vandalism and direct all their energies towards a single task -- burrowing a tunnel under the fence at one end of the abandoned playground. As the narrator watches their struggles and their eventual success, he knows that there is hope for he and Clancy as well. In order to survive the couple must give up their adult fighting and posturing and return to the simplicity and play of childhood.