Both of them were handcuffed together, and I don't understand what the underlined means. What did he bind to his companion's left bracelet?
Hearts and Hands by O. Henry
He slightly raised his right hand, bound at the wrist by the shining "bracelet" to the left one of his companion. The glad look in the girl's eyes slowly changed to a bewildered horror. The glow faded from her cheeks. Her lips parted in a vague, relaxing distress. Easton, with a little laugh, as if amused, was about to speak again when the other forestalled him. The glum-faced man had been watching the girl's countenance with veiled glances from his keen, shrewd eyes.