The present research was aimed at investigating in a simulation experiment whether the initiation of a hostile project in an environment akin to airport security checkpoints would translate in variation of cardiac activity. Twenty-three participants (eight women) enrolled as mock passengers had to make several traverses of a security checkpoint while carrying luggage containing either a neutral or a falsely dangerous item. The traverses with the falsely dangerous item were associated with an elevation of heart rate and higher drops of heart rate variability than the traverses with the neutral item. These effects were more salient for the first traverses. Implication of results for security management and the role of arousal and mental workload in threat detection are discussed.