disgusting butterfly (swallowtail)

A swimming pool not unlike any other pool, a structure built of tile and cement and money, a backyard toy for the affluent, wet entertainment for the well-to-do. But to Jeb and Sport Sharewood, this pool holds mysteries not dreamed of by the building contractor, not guaranteed in any sales brochure. For this pool has a secret exit that leads to a never-neverland, a place designed for junior citizens who need a long voyage away from reality, into the bottomless regions of the Twilight Zone.