Legendary director Alfred Hitchcock once famously defined suspense as a moment in a story when two people are having a conversation at a table, and the audience is aware that there is a bomb under the table; the audience has a sense that something bad is going to happen, even if the characters don't, and the experience of watching the scene is an uneasy waiting game. Suspense involves a feeling of foreboding, of waiting for the other terrible shoe to drop, and it's a crucial part of several different film genres. y6d1h
A suspense film can be a horror movie, filled with ghosts or monsters, or it can be a crime thriller inhabited by killers or terrorists. It may even be a quiet psychological or courtroom drama. The crucial element is that the plot builds tension, rather than simply relying on action, thrills or violence. Suspense is more about being unsure what's going to happen ' and being at least a little afraid of what might happen ' than it is about being surprised or excited about what's happening. A horror movie that reveals its monster early on, then watches as it conquers its victims is an exercise in terror; a horror movie that hides the monster from us and makes us wonder which corner it's lurking around is dealing in suspense.
