What is the main problem and solution of the story of from the mixed files of Mrs basil e Frankel?

The main problem in "From the Mixed-Up Files of Mrs. Basil E. Frankweiler" is Claudia and Jamie becoming runaway siblings who hide out in the Metropolitan Museum of Art. Their solution to this predicament involves uncovering the mystery of a new museum acquisition and deciding to return home with newfound appreciation for their family and each other.