Tucker (Stanley Tucci) is an accomplished novelist, and as his ability to recall words goes, so goes his identity. Writer/director Harry Macqueen beautifully illustrates this descent when Sam (Colin Firth) discovers a notebook containing Tucker’s next novel. As Sam flips through the pages, lucid, legible handwriting with sharp corrections and edits devolve into sloppy penmanship, garbled prose, and flat scribbles; then scratches, torn pages, and blankness. It’s the loss of the mind writ in the pages of a journal. The whole of Supernova reflects that moment: spare, quiet, and sad. But Tucci and Firth are excellent, and the movie earns its premise.