Nick Carter Stories No. 148, July 10, 1915; The Mark of Cain; or, Nick Carter's Air-line Case

In the bustling heart of a 1910s telephone exchange, the famed detective Nick Carter finds himself drawn into a puzzling crisis. A young switchboard operator, Helen Bailey, collapses in the middle of a call, her terror‑filled stare hinting at a hidden danger that has already reached the wires. Carter’s keen eye catches the fleeting expression that suggests a life‑or‑death secret being whispered over the line.

As the other operators gasp and scramble, Carter steadies the scene, demanding fresh air and water while his mind races to decode the frantic question, “Did they get him?” The clue points to a possible kidnapping or a lethal plot tied to the city’s shadowy underworld, a network that reaches from opulent mansions to grimy dive bars. With his trademark speed and intuition, Carter begins to trace the invisible threads of the conversation, determined to locate the missing person before the next call seals a fate.

The tension builds as every plug click could reveal the next clue. Listeners are treated to a blend of suspense and swift detective work that keeps the mystery alive.