Basic storyline

There are several storylines overlapping and eventually I've got to pick one and go with it, if it doesn't work it will mean major re-writes, but that's just the way it is.

The first over-riding theme or plot is that the main character wants to kill the devil.
Along-side this is the backdrop to the story which is the bombing of the Kaaba.
Along-side this is the love story element between the main character and the next sub-plot which is the introduction of Jinn.

For those who don't know:
Kaaba is the cuboid building in Mecca, Saudi Arabia which is the central point which determines the direction in which muslims pray, and forms the focal point of the once in a life-time pilgrimage. If it was actually bombed in real life - well I imagine it'd be like '9-11' multiplied by infinity.
Jinn are a little trickier. They are a parallel lifeform in this universe who are semi-invisible to humans and semi-dangerous for our health. They have a society of their own and worship God and everything - generally seen as responsible for possessing people, or causing evil/bad things to happen if you get involved with them.


A general outline is as follows:

[bombing of Kaba]
[main character looses wife - whole family]
[decides to kill the devil]
[enlists help of jinn]
[falls in love with female jinn]
[decides to kill the devil during ramadhan when the devil is chained to the gates of hell - hence has 'one lunar month' to acheive this]
[travels to hell]
[finds and fights the devil]

There's a lot of unanswered questions in my mind and I don't really know how or where to start with the writing. This storyline has a lot more detail, which I will add to and flesh out - the main unanswered questions are however: how will my main character journey or find hell and then when he does how will he fight and kill - or not - the devil?
Remember all the basic elements of this book exist in the Islamic faith, so it does have to have some element of 'realism' - not too fantastical. I'm sure I'll figure something out eventually. As the storyline develops I'll show the development in subsequent blogs called 'storyline01, 02, 03 etc.' I won't delete any or edit them afterwards.

But soon I have to get actual writing - and I'm really not sure where to start.