All of the action in Without Warning takes place over the course of a 12-hour period. Terrorists have infiltrated a chemical plant and a three-man team gets inside to take them down. Along the way there are three civilians that play a role in the operation as well. One is a security guard, another is a secretary, and the third is a cameraman who survived a crash in his news chopper after it was hit by a surface-to-air missile from the terrorists. The cameraman wants to get the story and survive while everyone else wants to get out of there and save as many hostages spread across the plant as possible. There are six playable characters in all, but the trick is that none of them really interact with each other directly. However, there will be several times where characters see others or the results of their actions during their own segment, such as seeing a firefight from afar.