This blockbuster did more than provide last summer's most satisfying movie experience: it reaffirmed Harrison Ford's position as the most reliable action star around. This film is the third and easily the best and most tightly wound of the Tom Clancy yarns about CIA analyst Jack Ryan. If "Danger" has a problem, it is that it starts too slowly. But the pleasantly complex story line, set in Washington and Colombia, twists and turns in unexpected ways. Keeping this complexity involving and fast-moving is director Phillip Noyce. What is rarer than good action, though, is plausible dialogue and acting, and these are the film's key strengths (HBO Saturday at 8 p.m.).