PLOT
Is when the 3 girls get kidnapped on Melody's 4th birthday, but Ali and Lilly are taken for collateral damage. The main reason why Melody was targeted is because Will hated JJ being married to Rossi and basically he wanted to punish JJ and Rossi. Now the reason why Ali and Lilly were only for the opportunity to torture Alex and Emily and the team by stealing their daughters.
PLACE
Will be held in a a warehouse across the street from the BAU
WHO
Kevin, Anderson, and Will
WHY
Because of jealously and anger