Surprise is often thought of as an experience that is elicited following an unexpected event. However, it may also be the case that surprise stems from an event that is simply difficult to explain. In this paper, we investigate the latter view. Specifically, we question why the provision of an enabling factor can mitigate perceived surprise for an unexpected event despite lowering the overall probability of that event. One possibility is that surprise occurs when a person cannot rationalise an outcome event in the context of the scenario representation. A second possibility is that people can generate plausible explanations for unexpected events but that surprise is experienced when those explanations are uncertain. We explored these hypotheses in an experiment where a first group of participants rated surprise for a number of scenario outcomes and a second group rated surprise after generating a plausible explanation for those outcomes. Finally, a third group of participants rated surprise for the both the original outcomes and the reasons generated for those outcomes by the second group. Our results suggest that people can come up with plausible explanations for unexpected events but that surprise results when these explanations are uncertain.