Suspense is an affective state that contributes to our enjoyment of experiences such as movies and sports. Ely, Frankel, and Kamenica (2015) proposed a formal definition of suspense which depends on the variance of subjective future beliefs about an outcome of interest (e.g., winning a game). In order to evaluate this theory, we designed a task based on the card game Blackjack where a variety of suspense dynamics can be experimentally induced. By presenting participants with identical sequences of information (i.e., card draws), but manipulating contextual knowledge (i.e., their understanding of the rules of the game) we were able to show that self-reported suspense follows the predictions of the model. Follow-up model comparison further showed an advantage for the “suspense as variance of future beliefs” account over a number of alternative definitions of suspense, including some that depend only on current uncertainty (not the future). This paper is an initial attempt to link aspects of formal models of information and uncertainty with affective cognitive states.