A to Z Challenge - E is for Envelope

The A to Z challenge is to write a daily blog post centred around a different letter of the alphabet each day. I will attempt to write a complete story which will continue each day and hopefully draw to a conclusion when we get to Z.
Are the box and the finger somehow related to Mr Summers’ job as the head of a research lab?
For previous posts click a letter - A , B , C and D



DI McDonald walked into the lab to find all the letters laid out on a large table. They looked as if they had somehow be...