Max and the Chief are in a library, looking for a top secret book the Chief has compiled containing information about all the agents of CONTROL. After a short battle with a KAOS agent, the Chief and Max find the book.
Back at CONTROL HQ, in the Chief's office, Max and 99 are told by the Chief that the book must be kept safe at all costs. 99 suggests a safe deposit box in a bank so Max and Larabee take the book in an armored truck to the bank where they put it in a vault. While the Chief and Larabee are inside, Max accidentally closes and locks the vault door when he leans on it. The manager explains that the time lock will only open the door next Tuesday, and there is not enough air to keep the Chief and Larabee alive until then.
The Chief sends Max and 99 to the prison for Baffles, a world famous safecracker. However, they are too late (Baffles is being executed) and return with Freddie the Forger instead. Freddie injects ink from a fountain pen into the vault's timing mechanism causing it to advance to a point equivalent to "next Tuesday" and thus opening.
The Chief and Larabee are freed but Larabee is locked in again when he reenters to get the book and the manager unknowingly closes the vault on him.
- Maxwell Smart - Don Adams
- Agent 99 - Barbara Feldon
- The Chief - Edward Platt
- Larabee - Robert Karvelas
- Foster - Dick Yarmy (uncredited)
- Harrington (uncredited)
- Dunlap (mentioned)
- Freddie the Forger (Freddie) - Ned Glass
- C. Barton Neff - Herbert Voland
- Hermione Becker - Ann Summers
- Baffles (mentioned)
The stakeout sequence includes footage recycled from Episode #117: "The Treasure of C. Errol Madre".
The title refers to the Broadway musical Do I Hear a Waltz?.