Leave the office and go to Randal's flat. Use the business card to open Mortimer's door. You want to take Millennium Enterprise's model.
Close to the fireplace. Move the log. You will hear ticking - as long as it lasts you can open the top drawer in the desk with model. You can see number 1 and three buttons: red, green and blue. Push one of them (e.g. red).
Look at the bookcase and push the red book (if you pushed the red button earlier) as the first one. The further sequence doesn't matter.
Now open the medium drawer with number two. Push the button (other color that the one you pushed before, e.g. green). Then push any book as the first one and as the second one push the book green (if you choose the green button).
Open the bottom drawer with number 3. Push the button (other color that the one you pushed before, e.g. blue). Then push any book as the first and the second one, then push the book blue (if you choose the blue button).
Look at the half-open panel on the bottom shelf. Take a key and use it with the lock to open the showcase. Take a miniature.
For solving this puzzle with first try you will unlock the achievement 'Survival horror lover'.