Des Measures has broad shoulders but even they are beginning to buckle under the burden he is being forced to bear, through caring for his elderly uncle.
Des feels duty-bound and morally obliged, but the trials and tribulations related to his relation are testing him to the very end of his tether, and then some. The old adage says that blood is thicker than water, which makes Des's situation even more dire, since he is related to the old man through marriage, not blood.
So when someone suggests that if his uncle was a poorly pet, he would be put to sleep, Des is faced with a crisis of conscience, and his family loyalties are tested to the limits in this black comedy — riddled with puntastic one liners — of the ages. Or of the aged!
