On the very same day that Allison begins getting to know Sam, the mysterious new guy in school, she learns that Izzy's been diagnosed with brain cancer and has only a few months to live. Allison just can't find the right time to tell her best friend about her burgeoning romance, especially when Izzy develops a crush on Sam herself. Then Allison decides to make her best friend's last days truly unforgettable by convincing Sam to become Izzy's boyfriend instead of her own.