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

"The Mark of Cain; or, Nick Carter's Air-Line Case" edited by Chickering Carter, throws the famous detective Nick Carter into a whirlwind of mystery and personal drama when he meets Helen Bailey, a young telephone operator clearly troubled by her brother Bart's criminal life. After Helen faints while eavesdropping on a suspenseful phone call, Nick is pulled into her world, where he tries to sort out a series of clues surrounding multiple thefts and Bart's involvement with the police. Nick's intuition is put to the test as he navigates a complex web of deceit, attempting to protect Helen while uncovering the truth behind the crimes. The story begins with a dramatic situation, making it clear that Nick's intelligence will be necessary to find out the truth.