It's one of the most frustrating things in the world--remembering the plot or stars of a movie but being unable to put your finger on the exact title. Before the rise of the Internet, you needed to do a lot of tedious research or hope you ran into somebody who could provide the name of the movie with just a description. But nowadays, you can use the plot description or character description to search for the movie name quickly.
Click on the "Plots" option in the search window, then type in key phrases connected to the plot. Examples of key phrases include "spy movie," "romance" or "explosions." Try to be as detailed as you can and include as many key phrases as you can. The engine will then take you to a list of plot summaries that include those key phrases. Sift through them until you find the one that matches your movie.