The plot for the original anime is as follows (from Anime News Network):
A new threat appears all over the world in the form of the terrorist group known as the Galactor. To combat the forces of Galactor, well-renowned scientist Kouzaburou Nanbu unleashes theScience Ninja Team Gatchaman, a team of five young heroes skilled in the art of ninjutsu and dressed in unique bird-like costumes.
The movie stars Tori Matsuzaka (Samurai Sentai Shinkenger) as Ken the Eagle, Go Ayano (Kamen Rider 555, Rurouni Kenshin) as Joe the Condor, Ayame Goriki (Mirai Nikki, Black Butler) as Jun the Swan, Tatsuomi Hamada (Ultraman Zero, Gokaiger vs. Gavan) as Jinpei the Swallow and Ryohei Suzuki (Hentai Kamen) as Ryu the Owl.
The movie will be directed by Toya Sato (live-action Grave of the Fireflies, Gokusen), Yusuke Watanabe (Gantz, Dragon Ball Z: Battle of Gods) will write the script and Shinji Aramaki (Appleseed) in-charge with the character designs.
The film is out August 24th in Japan.
For your Entertainment- Various Gatchaman Intros