The session will start by asking children their favourite adventure, mystery, suspense stories and to find out what techniques they know that writers use to write with tension and suspense. 
I'll then read a passage for them to hear an example of this. On the screen I will have typed 4 passages showing different styles of writing. Some will use simple sentence structure, some with over use of connectives and some very long, over detailed sentences. Each time children can rate the passage out of 10 for how effective it is for creating tension. We will then read one which uses all of the above to show how using a mix of sentence structures can help create tension in a story.
Following this I will show a picture for inspiration for the children to write words and phrases to describe it and encourage and model the use of similes and personification. Children can spend time after the session writing their Hallowe'en themed story.
Please have pens/pencils and paper to write on. Highlighters or coloured pens are helpful too.