Well lets start with the basics. The real title of this movie is "The Explosive Dragon Fist". It's about Hildegarn, who by the way isn't a dragon...(I'm getting all this info from the Japanese movie with English subtitles) Anyway the move gives no real hints as to its chronology within the dragon ball z story line other than the fact that Gohan is already doing the whole Great Saiyaman thing so its probably after movie 12. (duh) I'm too lazy to explain the entire story from beginning to end but heres the readers digest version: On a far away planet called Konats in a far away galaxy thats really far away, some idiots practicing black magic wished for their big ugly evil idol to be brought to life (aka a mix between Pinocchio and Godzilla). Anyway the beast they brought to life was called Hildegarn. Hes unstoppable about a day, when two kids use their magic flutes to weaken him (wow they pick up weaknesses fast on that planet). Then they use magic swords to cut him in half (wow some fast blacksmiths on this planet too). Somehow the flutes trap the two halves (head to waist/waist down) inside their bodies. Then finally the enders get involved and decide that the two brothers who saved the planet should be locked in music boxes and sent to the two ends of the universe. (gee interesting way of showing gratitude). Moving on, the two brothers (Tapion and Minoshiyal) are sent to the far ends of the galaxy. About 1,000 years later, one of the dudes that brought the beast to life, who had been traveling from planet to planet looking for the brothers, found the younger brother and killed him. (minoshiyal, cuz who wants to base a story around a person with a name that hard to pronounce) Thus the lower half of Hildegarn was released. (legs and tail) Later the evil guy finds Tapions music box and goes to earth, where he tricks Gohan into using the dragon balls to free Tapion, who has a hard time keeping the upper half under control. (If he falls asleep, it escapes and tries to kill him) But freeing Tapion meant the super special music box which kept Tapion locked away was destroyed. So to help him, Bulma tries to construct a new one but it doesn't work. Tapion, thinking it's OK to sleep, falls asleep and the upper half of Hildegard unites with the lower half and the full Hildegard wreaks havoc on the town. The Z-squad tried and fails to beat it, then Goten and Trunks fuse and goof around, then after being yelled at by Picollo, they attack Hildegarn and it seems like they've won. But (dun dun dun) Hildegard sheds his ugly skin like a beetle and becomes even uglier than before (if thats possible). The only difference is that now, he has wings. Yay. So anyway he kills more stuff and at the last minute when all hope seems lost Goku goes Super Saiyan 3 and says some cheesy line before doing this awesome punch (evidently a dragon fist) where he flies up in the air and the dragon that comes out when someone summons the uses the dragon balls (the ones on earth) appears in gleaming gold like Goku's hair, and flies right through Hildegarn's torso, leaving a giant hole the size of the Roman Colosseum, which obviously kills him. So yea, yay, Goku won as if you had any doubts. I know it was a bit long but it's a complicated story. There are a lot of other details i left out so you wouldn't be reading an article the size of a harry potter book, but when the movie comes out, it'll just be more interested to watch.
