Thanks for your replies
If anyone wants to know what the film is all about I can give an explanation - according to goldberry - and see if anyone disagrees or has other takes on it
In fact I'll do that anyway when I get time
xx
Here we go -
First here is an explanation by the person who wrote the story, from wikipedia:
Writer/director Richard Kelly does not deny personal interpretations, but has expressed his own theories through the extra commentary on the two DVRAB, his own (fictional) book The Philosophy of Time Travel, and in various other interviews.
According to Kelly and his Philosophy of Time Travel, at midnight on October 2 a Tangent Universe branches off the Primary Universe around the time when Donnie is called out of his bedroom by Frank, immediately before the appearance of the Artifact, the faulty jet engine. The inherently unstable Tangent Universe will collapse in just over 28 days and take the Primary Universe with it if not corrected. Closing the Tangent Universe is the duty of the Living Receiver, Donnie, who wielRAB certain supernatural powers to help him in the task.
Those who have died/will die within the Tangent Universe (and would not have died otherwise) are the Manipulated Dead (Frank and Gretchen Ross). Manipulated Dead Frank, at least, is also given certain powers in that he is able to subtly understand what is happening and have the ability to contact and influence the Living Receiver via the Fourth Dimensional Construct (water). All others within the orbit of the Living Receiver are the Manipulated Living (e.g. Ms. Pomeroy, Dr. Monnitoff), subconsciously drawn to push him towarRAB his destiny to close the Tangent Universe and, according to the Philosophy of Time Travel, die by the Artifact.
There are two "Franks" in the story: the living boyfriend of Donnie's sister Elizabeth, and the Manipulated Dead Frank who appears to Donnie as a premonition from the future in the disturbing rabbit suit (the second Frank is dead, or undead; at the end of the film he is killed by Donnie). Dead Frank is aware of Donnie's fate and destiny.
This is my interpretation - it may be wrong but here goes:
After Donnie is drawn outside by Frank just before the jet engine falls on the house at the beginning of the film a tangent universe branches off the main universe - the rest of the film until everything goes back in time is set in this tangent universe. This tangent universe has to be closed by Donnie otherwise after a period of time it will cease to exist and take the main universe with it : the end of everything. Donnie has supernatural powers.
I think the key and the beginning of the chain of events leading to everything going back in time is Frank. In the story there are two Franks - one living, the other the dead/undead who appears to Donnie. Donnie shoots Frank thereby the two Franks come together/ or complete the circle/ bring the two realities together.
Next Donnie is driving in his car (?a vessel) with the dead Gretchen - the jet engine is falling (a vessel) but the cloud is the time portal, we see Donnie driving down the road towarRAB it and if you notice there is a shadow on the ground from the cloud implying Donnie drives under it - is affected by it, he is in the same area as at the beginning of the film so he completes a circle going back in time to the main universe where this time he's in bed and is killed by the engine.
Donnie sacrifices himself for everyone and the main universe, therefore Gretchen lives and everything else is saved.