The Voice of the Tower

For the past few days, a strange rumor has been hovering in the streets of old Tours. A voice, like a lament, is said to have been heard at certain times coming from the Charlemagne Tower. Of course, the city officials have checked everything but found nothing unusual. Yet, the rumor grows, the voice is heard, night after night, and now day after day. There is only one solution left for the city and the lovers of the Tower: to call on you, specialized investigators, eminent discoverers whose reputation is no longer to be made, to uncover the secret of the "Voice of the Tower", which has been on everyone's lips for days...