Jumping the shark

   Jumping the shark refers to a point at which a TV series makes a desperate bid to improve its rating by introducing a melodramatic or fantastical plotline. I only found the expression recently but the phenomenon has been known for years. The phrase was coined in the 1980s when The Fonz tried jumping a shark on his water-skies when the ratings of Happy Days were falling.

Nowadays the plots of soap operas are so fantastical from the outset that I'm not sure how much more melodramatic they could be made.  A nuclear strike perhaps.  That might be their best fate!