Ptolemy Grey is a 91-year-old man, suffering from dementia and living as a recluse in his Los Angeles apartment. Then Robyn Small, a 17-year-old family friend, appears and helps clean up his apartment and straighten out his life. A reinvigorated Ptolemy volunteers for an experimental medical program that restores his mind, and he uses his last days--shortened now by the medical experiment--to delve into the mystery of the recent drive-by shooting death of his great-nephew, Reggie.