Gr 3-5-Mimi is a mystery writer who travels the world with her husband, "Papa," and their grandchildren Christina, 10, and Grant, 7. In Pyramid, the four travelers arrive in Cairo and are immediately thrown into a sinister mystery involving gun-toting thieves and deadly threats. The children are pursued by would-be tomb robbers and help solve the mystery when they run straight into the arms of Papa and a policeman. In Colosseum, Christina finds a mysterious message in a newspaper and immediately notices men in black trench coats everywhere. Unbeknownst to Mimi and Papa, the siblings try to solve the puzzling message that warns of a strange happening at the arena. With their new friends Luigi and Francesca, they explore the country, enjoy Carnivale, and discover that what they thought was a sinister plot is actually an audition for a movie. Both stories contain interesting facts about the history and culture of the settings. The story lines are similar, with interesting beginnings but disappointing endings. Surprisingly, Grant and Christina receive little adult supervision as they wander the foreign cities. Mary Pope Osborne's "Magic Tree House" series (Random) is a better choice for adventure lovers.-Alison Grant, Ruby S. Thomas Elementary School, Las Vegas, NV Copyright 2006 Reed Business Information.