The Secret Number

A psychiatrist is compelled by his patient, an institutionalized mathematician, to consider the existence of a secret integer between three and four. Doctor Simon Tomlin, a psychiatrist in a mental hospital, has a disturbing conversation with one of his patients-- a brilliant mathematician named Ersheim, who intends to prove the existence of a secret integer between three and four. Tomlin is compelled to dig deeper, but he only uncovers more questions. When Ersheim mysteriously disappears from the hospital, Tomlin realizes that their fates are deeply entwined. ("The Secret Number" by Colin Levy)