HOW TO PLAY

A £25,000 reward MUST be won each week for four weeks! Will you be this week’s clever detective in our fourth and final whodunnit?

Each Saturday we have published a new crime story. It introduces a group of suspects, and the picture of the crime scene that accompanies it also contains a visual clue. Along with the picture and the story comes the first of six principal clues that, together, will help reveal the identity of the killer.

The first clue in today’s case, an image that came in a dream of a train with smoke coming out of it in the shape of a question mark, is reproduced on this page (above). Each day from Monday to Friday in the Daily Mail we’ll publish further clues, all of which have a common thread that relates to the killer’s name. On Friday, as well as the final clue there will be extra information to help you crack the mystery – together with instructions on how to enter for the £25,000 prize.

Once you’ve worked out who the killer is, send the answer by phone, text or email when the competition lines open on Friday morning. The lucky winner with the correct answer will be drawn at random on Saturday 16 December and called between 12 noon and 2pm. Answer the phone to accept the £25,000 reward. To be eligible to win, you must have retained four front pages from the Daily Mail between Saturday 9 December and Friday 15 December.

Entrants to this competition must be UK residents (excluding Northern Ireland, Channel Islands and Isle of Man) aged 18 or over.

Terms and conditions apply, please see the main newspaper today or visit dailymail.co.uk/mystery.