There are only three books in The Hunger Games “trilogy” but Lionsgate, the studio behind the release of the movies, got greedy – as did Warner Bros. with their Harry Potter film franchise – and divided the final book, Mockingjay, into two movies.
Lionsgate also did the same with the book Breaking Dawn, releasing the movie in two parts.
The studio, Lionsgate, uses the moniker “The Hunger Games” to precede the accurate titles of the second, third and fourth movies, Catching Fire, Mockingjay Part 1 and Mockingjay Part 2.
The books were not referred to as “The Hunger Games: Catching Fire” or “The Hunger Games: Mockingjay.”
Readers and fans of the series are quite aware without having their intelligence insulted to know that the movies are part of The Hunger Games franchise. (Lionsgate did the same stupid thing with their Twilight film franchise, having the tag line “The Twilight Saga” precede the title of each subsequent movie in the franchise).
Mockingjay Part 1 tells half the story of the book Mockingjay, the final book in The Hunger Games trilogy. In it, Katniss Everdeen (played by Oscar winner Jennifer Lawrwence) reluctantly becomes the symbol of a mass rebellion against the autocratic Capitol.