emil and the detectives

I decided to make a cover for Emil and the Detectives for Penguin design award because I wanted to have a quick turn abound brief; I don't know the book so I wanted to challenge myself with quick research and idea development.
It's a children's book, set in Berlin 1929, about a boy (Emil) who was raised my his single mother. He is sent by her on the train with a lot of the money she has earned to give to his grandmother, he keeps it pinned to the inside of his jacket. But on the train he meets a mysterious man in a bowler hat who gives him some chocolate which makes him fall asleep, the man then steals the money. Emil tries to follow him; he then meets a group of 24 boys; they all follow the man and eventually get the money back.

I read this article about the story - http://www.telegraph.co.uk/culture/theatre/10441739/Emil-and-the-Detectives-why-it-is-a-childrens-classic.html
It talks about how the story isn't a 'sanitised fantasy' as it doesn't have an obvious moral ending like most children stories - making it quite contemporary for its time. It shows the children to be the heroes, and showing them to be 'as clever as their adult counterparts'. It is also a story of a child becoming stronger - he enters Berlin a young, frightened, poor country boy and by the end he is strong and confident. 

Some of the main imagery I picked up on was:
mysterious/dodgy man, black bowler hat, 24 children, Berlin, big buildings, train, train station, money, bank robber, chocolate, bank, cafe

I had a look at other book covers for the book and they all have a pretty similar aesthetic:

All the covers I saw were yellow with a cartoon-esque Emil and boys. I think for this Penguin competition they are looking for something different from all the other designs - something more contemporary, as all the covers I saw looked a bit dated, as it is an old story. 

These are some of the initial ideas I had:

I thought it could be interesting to have no figures on the design, just footprints - to show the chase that runs throughout the story, there would be lots of little footprints catching one set of big footprints

I like the idea of showing the boys chasing the man of the front cover, and then maybe having a magnifying glass on the back to highlight the detective element 

The magnifying glass could make the design too busy, so I could also have mini versions of the boys running around the blurb instead - that way it will be like carrying on the design from the front

I also thought about making the whole cover into the outside of a train, and inside the windows you could see the boys running and the man just jumping off the train - that could be a fun idea to have the the design as one big image, although it will be harder to fit in the blurb and other writing

I tried doing the children's book cover for penguin last year for 'Carrie's War' and although I liked the cover image, I thought the actual design of the cover was pretty bad - my choice of font and its colour really didn't work and I didn't put much thought into how it would be laid out. So for this I want to make everything work together - try and include the text with my illustrations somehow.