The note, once opened, details thus:

Lanyon, after the final dinner party, received a most troubling and strange letter from Dr. Jekyll. The letter requested Lanyon to, with the help of Poole, break into the upper room of his laboratory and take a particular drawer home with him in order to give to a man that’ll arrive at his house come midnight. The letter also mentioned that, if he did as asked, he will learn all. 

Lanyon agreed and arrived at Jekyll’s home, where he met Mr. Poole and a locksmith that aided them in entering the laboratory. The drawer was quickly collected and Lanyon returned home. 

Whilst home, Lanyon inspected the drawer, observing a number of vials, one with a strange red liquid inside especially. He also discovered a notebook, documenting a series of experiments and their results but offered little insight into the purpose and methods of such trials. 

At midnight, a man did appear, who was Mr. Hyde. However, Lanyon had never met Edward and, therefore, thought little but still debated Dr. Jekyll’s sanity. Hyde was intent on the drawer and demanded a glass to mix the contents together, forming a purple substance that quickly became green. 

Hyde then asked Lanyon whether he should leave and consume the liquid elsewhere, away from his eyes, or quaff it in front of him, warning that it will shock him intensely. Lanyon, being heavily wrapped up in the mystery himself, could not allow such a sight to be unseen, his curiosity had gotten the better of him. 

Drinking the liquid, Hyde informed Lanyon that his skepticisms will be crushed. Downing the contents, the form of Hyde began to mutate, his body expanding, features deforming, until the previous figure of Hyde was gone, replaced by Dr. Jekyll. The letter ends but Lanyon does state that witnessing such a thing will surely kill him, as his whole understanding of science and so forth has been wrecked.