When the world's oldest man dies at a retirement center, Stottlemeyer's wife Karen insists that he investigate even though he--and everyone else--figure the man died of old age. Meanwhile, Karen kicks Stottlemeyer out of the house after a fight and Monk has him stay at his place.

A series of mail bombs target three wealthy siblings, but Monk thinks one of the brothers is actually responsible. The problem is, he's been in a coma for the last four months.