The children rent a post office box, though it costs a scandalous four dollars and fifty cents. Jamie signs the forms with a fake name; now, they have a source to receive anonymous communications about their discovery.
The next step is to deliver the letter to the head of the museum. It's not entirely safe for either Jamie or Claudia to deliver the letter, so they decide to find another child from a tour group to do it for them.
They hear a class chatting in the Egyptian wing, and trail them. However, they slowly realize how familiar the voices are, and they realize that it is Jamie's third-grade class, come to visit the museum. Claudia shushes Jamie, who is very annoyed that she would assume he would do anything rash. Annoyed, Jamie considers doing something very rash: sneaking back home with the class. Claudia says that this is actually a perfect opportunity, because it allows Jamie the chance to go to the museum office himself and deliver the letter - he can just say that he's a member of a class that was visiting and his teacher asked him to make this delivery.
Jamie does so successfully, and then he and Claudia head outside into the crowd on Fifth Avenue.
Claudia and Jamie stroll around New York as they eagerly await a reply to their letter, even though they know that no one would reply so quickly.
They decide to take a tour of the United Nations. The woman at the ticket counter asks if school is out today, and Jamie answers with a convoluted story about a boiler exploding in the school. Claudia drags him off, though she is very impressed that he had such a detailed story ready.
Their guide is an Indian woman who wears a sari, and Claudia is very impressed with her. Like this woman, Claudia wants to find a way of being different. She mimics the guide's way of walking and speaking, but Jamie just teases her. Claudia decides she will have to discover some other way of being different, perhaps by solving the mystery of Angel.
The children stop by the post office box once again, and discover a letter waiting for them.
The contents, however, are rather disappointing. It turns out that the museum has long been aware of the mark at the bottom of the statue, but this does not necessarily mean that Michelangelo carved the statue: it is possible that it was added by a counterfeiter later, and moreover, Michelangelo did not add the mark to every statue he carved. The statue may have been designed and carved by Michelangelo; it may have been designed by him but carved by someone else; or it may have been neither carved not designed by him. The statue has been examined by a number of experts, and the museum is waiting on the arrival of several more. The letter notes that there is evidence that Michelangelo carved some sort of statue for his own pleasure, but no one knows exactly what it was. The letter is not even from the director of the museum, but is instead from one of his subordinates.
Claudia and Jamie are deeply disappointed. Claudia cries a great deal, and then the two try to decide what they will do next. Claudia is determined to solve the mystery of the statue so that she can go home different. Jamie notes that if even the experts don't know, how can a child be expected to figure out the origin of the statue? Claudia might be using this as an excuse to feel dissatisfied.
The two go to the ticket counter for the commuter rail to purchase tickets home. As they are about the purchase tickets, Claudia blurts out that they would like two tickets for Farmington, Connecticut - far from their home in Greenwich. Claudia explains to Jamie that she wants to visit Mrs. Basil E. Frankweiler, from whose collection the statue of Angel came to the museum. Perhaps Mrs. Frankweiler will have some clues for them. Jamie is stunned, but Claudia explains that she has a hunch that that Mrs. Frankweiler will tell them everything they need to know about Angel. Jamie comments that she never has hunches - she always plans everything. Claudia says that she has most certainly had hunches before.
Jamie buys the tickets to Farmington, and Claudia notes that he didn't ask the prices for the tickets - and he always asks prices for everything. He replies that this is probably not the first time he failed to investigate the price of something.
The two children enjoy the train ride, and take a taxi to the home of Mrs. Frankweiler.
In Chapter 7, the children are given an unexpected reminder of home: Jamie's third-grade class visits the museum! This allows the children to deliver their message to the museum directory, because they can just say that they were part of that tour group. Impressively, Claudia is able to turn this risky situation into an advantage.
Unfortunately, the children are hit with devastating news. The museum is well aware of the mark at the bottom of the statue, and it is not sufficient evidence to determine that the statue was carved by Michelangelo. Claudia in particular is devastated by this news. She cries and comments that “I feel as if I jumped into a lake to rescue a boy, and what I thought was a boy turned out to be a wet, fat log. Some heroine that makes. All wet for nothing” (pg. 118).
Claudia compares her struggles of proving the authenticity of Angel to the effort of rescuing a boy. However, all her theories about Angel have turned out to be worthless, just as the boy in the analogy turned out to be nothing but a log. This analogy also highlights Claudia's desire to be a heroine: she wants to do the rescuing, in contrast to the girls in fairy tales who are often rescued.
Chapter 8 also makes clear Claudia's central motivation: she wants to feel different, both from other people and from the person that she was when she left home to run away to the Metropolitan Museum of Art. She hopes that discovering the true origin of Angel will help her achieve this goal.
When Claudia suddenly, impulsively purchases tickets to Mrs. Frankweiler's home in Connecticut, Jamie comments that she never has hunches; she replies that she's had them before sometimes. Jamie does not ask the price of the tickets, which surprises Claudia; he replies that there was some earlier purchase he didn't price before buying. In each case, the children are acting out of character, yet claiming that this is entirely in keeping with things they have done in the past. Have their characters been changed by their adventure in the Metropolitan Museum of Art, or are these impulses qualities that they have always had? This raises interesting questions about the origins of personal change and growth: if we seem to change, were those changes really a part of us all along?