Sentence:  "She twisted her hands behind her; / but all the knots held good! / She writhed her hands till her fingers were wet with sweat or blood! / They stretched and strained in the darkness, / and the hours crawled by like years, / Till, now, on the stroke of <WSD>midnight</WSD>, / Cold, on the stroke of <WSD>midnight</WSD>, / The tip of one finger touched it! The trigger at least was hers! 
Meaning of the word marked with <WSD> tags:  12 o'clock at night exactly.