This is the second in a series of nine novels based on the television series "Get Smart". This book tells the story of Maxwell Smart, and his female partners Agent 99, as they try to find a scientist named Dr. X, on a ship. They must stop him from selling a invisibility formula to the villainous group KAOS. Helping them is Agent K-13, Fang the Spy Dog. Besides the formula Max, 99, and Fang must also locate the experimental guinea pigs, that are now invisible. The cover of this book was also used for the 7th issues of the comic book. This second book was released in February 1966, about a five month after the television show premiered.

Get Smart, books by William Johnston, each book was originally priced at 60¢;
1. Get Smart! #T-103
2. Sorry, Chief... #T-119
3. Get Smart Once Again #T-121
4. Max Smart and the Perilous Pellets #T-140
5. Missed it by That Much #T-154
6. And Loving It! #T-154
7. Max Smart - The Spy Who Went Out to the Cold #T-159
8. Max Smart Loses CONTROL #T-174
9. Max Smart and The Ghastly Ghost Affair #T-191