It's a Lisa Simpson double feature!
First, after being pressured by her peers to join the new baby-sitters union, Lisa violates the rules and watches her own sister without a contract and is summarily kicked out. As a result, Maggie gets lost in the red tape of organized labor. But when Lisa decides to find her sister by busting the union wide open, she discovers an insidious plot against the youth of Springfield!
Then, explore the subterranean catacombs that lie beneath Springfield Elementary as Lisa goes in search of...missing school supplies.
by Boothby, Lloyd, Bavington, King, Steere