The tenet is simple. At all points during which the story is being told, the audience must--at the beginning, throughout, and at the end of every scene--always want to know "what happens next."
This might seem like a simple feat, but I can honestly say that less than five percent of mainstream films accomplish this throughout their entire duration--and for novels, the percentage is even lower. For spec scripts, forget it--the figure is less than one percent (I say this as a former script reader).
During the 18th and 19th centuries, stories written by famous authors such as William Makepiece Thackeray, Charles Dickens, and Arthur Conan Doyle first appeared in a serial format, chapter by chapter, in popular magazines of the day. If their audience ceased to care about "what happened next," then the next issue of the magazine would go unbought, the story would be canceled, and the writer would cease to be paid. It was not until after these serials were completed that they were published in novel format.
This type of segmented storytelling continued into the 20th century in the form of radio serials, followed by movie serials (appropriately called "chapter plays"), and eventually episodic television, in which the "cliffhanger" became a device of supreme importance.

During the 20th century, the concept of the novel as "fine art" arose, obscuring the classic methods of storytelling. Certainly James Joyce and William Faulkner, as brilliant as they were, did not care a whit for holding their audience's attention. In the cinematic world, the rise of the "art film" had a similar impact upon the nature of popular storytelling. Filmmakers cared more about making their films seem profound than about telling a riveting story.
The principal of "What Happens Next" has not been wholly forgotten. Soap operas have recognized the power of the concept, and have integrated it (albeit artlessly and often ridiculously) into every aspect of their storytelling.
Dan Brown has also tapped into the power of "What Happens Next." Personally, I've always found his characters to be one-dimensional, his drama tepid, his research superficial, and his situations preposterous. He has nevertheless become a best-selling phenomenon simply by shortening his chapters to no more than a few pages, and by ending every single one on a cliffhanger.
Today there are still a small number of very talented individuals writing for film and television who understand and apply these concepts (in fact, the concept seems better understood by TV writers, who work in an inherently segmented medium). Unfortunately, these individuals are few and far between.
So take a look at your script. At the end of every scene (or chapter, if you are a novelist), have you given the audience a compelling reason to keep reading? If not, then you have some work to do.
Remember, it is not enough to simply employ a device such as "we just found out who the killer is, and have an appointment to dine with him in the next scene." If we do not care about the characters, then such a plot device is useless. You must first create compelling characters (more on this point later), and then repeatedly structure the scenes in a way that keeps the audience insatiably curious for more.
Do this in EVERY SCENE, and they'll stay in the theater for 90 minutes...or three hours...or keep reading till page 1000.