Joel-Brock Lollis's family has vanished into the labyrinthine Sporangium below a curious Georgia emporium, Big Box Bonanzas. Glimpses of an older J-B Lollis of the Atlanta Braves on a BBB television suggest that Joel-Brock may never get back his parents and sister. The Valorous Smalls--almost-ten Joel-Brock, lively teen Addi, and tiny detective Valona--forge their way into the mushroom realm to change that possible future.