Ulick hatches a daring plan to sneak inside the Sullivan household. With Prof. Miles on lookout, they try to find out what the key they found beneath the floorboards unlocked. Meanwhile, back in the library once again, Benson and Charlie discover just how dangerous Silver Nitrate can be...

Professor Miles retires for the night, trudging through the rain and darkness to Ulick's house, where his curiosity gets the better of him and he gets to know the Silvermines resident a bit more. Montgomery is left to wonder whether Ulick's stories of the púca are wholly true. And if they are, what would that mean? 

With the mysterious stalker revealed, Charlie and Prof. Miles conclude their business in Nenagh and re-join Benson and Ulick, who had a tense encounter with the police sergeant. With evening swiftly approaching, the investigators decide to head to Silvermines; Ulick's home village, and the scene of the crime. 

With the investigators briefed on the murder case, their leads bring Ulick and Benson to the police while Charlie and Prof. Miles follow-up on clues relating to the bizarre circumstances surrounding Jack Sullivan's death with the aid of the local library... But someone is following them. Watching them. 

Step back into 1919 Ireland, where four investigators are ensnared in a web of mystery surrounding a chilling murder in the small village of Silvermines, Tipperary. But as they begin the investigation, they uncover a truth most perplexing - the victim was apparently already dead before they were murdered. But... how?