What is the answer to Morse code in book 7 of 39 clues?

You're likely referring to the puzzle in "The Serpent's Shadow," the seventh book in the 39 Clues series. The Morse code puzzle appears in the chapter "The Serpent's Shadow," where the Cahills are trying to decipher a clue left by their ancestor, William Shakespeare.

The Morse code message is: "Beware the serpent's shadow."

This message warns the Cahills about the danger posed by the Shadow, the organization trying to collect all the clues.

The decoded Morse code is:

* .-- --- .-. .-.. -.. . --- ..- .-.. -.. .-.. .-.. --- -..

If you're stuck on another puzzle in "The Serpent's Shadow" or any other 39 Clues book, feel free to ask!