Three academics.
The first, Ren, a mathematician, arrives at Cambridge to complete a PhD but is desperate to keep his real intentions for study a secret.
The second, Ruth, Ren's supervisor, eager to rise through the ranks of the university.
The third, Diego, Ruth's husband, and a philosophy lecturer trying to save his department from budget cuts.
All is well, until Ren begins an affair with Ruth and then with Diego. The modern mnage trois explodes gender, love and sex and, using the lens of geometry, reveals equal relationships are indivisible by three.