This case takes place in an old dye works in South Buffalo New York. The name on the building is National Aniline, a now-defunct company, but this old plant was owned by a big chemical conglomerate, Allied Chemical. The events took place in the 1970's when the telephone network used mechanical switching and relays. The system was slower than our modern fiber-optic networks, but it was reliable.

Big companies like Allied Chemical used tie lines and other leased phone links to handle calls from one plant to another. Long distance calling was not the bargain that it is today. Their network linked its 8 locations across the US. One plant could link to another by dialing a 1 or 2-digit tie line code. Once the link was established, you only needed to dial the extension of the party at that site.