Bart takes Grandpa to class for a class project, but grows embarrassed when Grandpa seems to rant and rave like a lunatic.
Shortly afterward, Grandpa receives a letter that a member of his old World War II unit, The Fighting Hellfish, has died. Grandpa attends the funeral along with the other surviving member of his unit: Mr Burns.
Shortly thereafter, Mr Burns attempts to have Grandpa killed. Seeking refuge with the Simpson family, Grandpa gives scant details as to why they need to protect him. Later that evening, he finally reveals to Bart the sercret of The Fighting Hellfish:
The unit was charged with