Flowers for Algernon by Daniel Keyes $2.99
https://www.amazon.com/Flowers-Alger.../dp/B003WJQ74E
Winner of both the Hugo and Nebula Awards, the powerful, classic story about a man who receives an operation that turns him into a genius...and introduces him to heartache.
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Charlie Gordon is about to embark upon an unprecedented journey. Born with an unusually low IQ, he has been chosen as the perfect subject for an experimental r surgery that researchers hope will increase his intelligence-a procedure that has already been highly successful when tested on a lab mouse named Algernon.
As the treatment takes effect, Charlie's intelligenc e expands until it surpasses that of the doctors who engineered his metamorphosis. The experiment appears to be a scientific breakthrough of paramount importance, until Algernon suddenly deteriorates. Will the same happen to Charlie?