The Dead Drop is by Jennifer Allison. The fourth book in the Gilda Joyce series. Gilda lands a summer internship at the International Spy Museum in Washington, D.C. Once there, she discovers that the museum is haunted and that the ghost wants her to uncover a spy who is selling secrets to the Russians right under the CIA's nose. Fans of this series will enjoy this installment as well.
Ratings: 6th grade - 7 out of 10.