Lieutenant Niles' Report is a written note found in Dishonored.
Transcript[]
As requested, this is a sample of the black market elixir we believe to be coming from one of the abandoned distilleries. No doubt it's inferior to your formula, or even Piero's Remedy, but people are desperate. We have not been able to identify the additional ingredients. Perhaps you'll have better luck.
One thing of note: Some of the men of the Watch claim, when pressed, to have purchased and used this stuff from time to time since it's cheaper than either of the popular brands. None of them report any illness or complication. So while it may not protect from the plague as well, it doesn't seem harmful.
Lieutenant Christopher Niles
Second Dispensary Detail
Dunwall City Watch
Location[]
It can be found on the desk in the greenhouse above Sokolov's safehouse during the mission The Royal Physician.