Greg Heffley's on a losing streak. His best friend, Rowley Jefferson, has ditched him, and finding new friends in middle school is proving to be a tough task. To change his fortunes, Greg decides to take a leap of faith and turn his decisions over to chance. Will a roll of the dice turn things around, or is Greg's life destined to be just another hard-luck story?
哇，有了這顆命運8號球，我是不是可以出運了？
葛瑞發現好哥兒們榮利和雅碧嘉在一起之後，性格大變，頭髮還開始分邊，更糟的是，還把女朋友的話當成聖旨。於是，他們倆漸行漸遠，葛瑞決定開始尋覓新夥伴，但要在中學校園裡面找到一拍即合的好朋友，簡直比征服宇宙還難！
就在葛瑞一邊經歷各種社交尷尬情境，一邊忍受昔日好友不停放閃時，他意外找到一顆命運8號球，立刻像是找到了人生的救星，把生活大小事全交給這個神奇的占卜玩具。只是，葛瑞的連環衰運，有時候連命運8號球都愛莫能助……
——中文簡介摘自未來出版出版《葛瑞的囧日記 8：命運8號球》