Algernon is the laboratory mouse whom Dr. Strauss and Dr. Nemur use to test their experiments of enhanced intelligence. When Algernon begins showing remarkable signs of improvement by running the mazes they construct in record time, the physicians believe that their hypothesis has been proven: that is, it is possible to improve intelligence through scientific, medical intervention.
Strauss and Nemur soothe any ethical qualms they may have about their experimentation by selecting a human being of marginal intelligence: Charley. Because Charley has an extremely low I.Q., the doctors theorize that anything that they do can only help, not hurt, their subject.
Initially pleased by both Charley and Algernon's monumental success, the doctors hopes begin to falter when Algernon suddenly and precipitously begins a steady decline in his faculties. The doctors correctly surmise that Charley, too, will begin to lose his short-term gains in intellectual ability. Algernon, then, is a harbinger of what is to come for Charley.