杀 'kill' +
机 'mechanism / opportunity / impulse.' In wuxia and thriller contexts, the staple phrase is
暗藏杀机 /
杀机四伏 'hidden murderous intent / lethal traps everywhere.' Famous title use: 《
惊涛骇浪暗藏杀机》-type drama subtitles, and the Pixar short 'Lifted' was once dubbed with
杀机 in some fan subs.