cover story

1. A featured story in a magazine that concerns the illustration on the cover.
2. A false story intended to deceive or mislead: The spy's cover story required posing as a diplomat.

1.  A featured story in a magazine that concerns the illustration on the cover, as in The earthquake is this week's cover story for all the news magazines. [Mid-1900s]
2.  A false story intended to mislead or deceive; also, an alibi. For example, Their cover story while investigating local repair services was that they had just bought the house and were having problems, or The suspect gave the police some cover story about being held up. [Mid-1900s]