The new leader of a terrorist race of aliens called Stellairians wants to embark on a new era of peace and comes to Earth for negotiations ... bringing along his spoiled teenage daughter. The Stellairians age rapidly in Earth's atmosphere - about 100 years in a day - so Kima is reminded to take her hypo-spray, located on a chain around her neck. Kay and Jay are assigned baby-sitting duty, and take Kima to the mall - where a group of Frostifarian Kidnappers (who had their icy planet scorched by Skon) create a diversion and nab Kima. During the chase, her hypo-spray comes loose and accidentally exposes Kay to the anti-aging serum. As a result, he begins he did start to growing belly time to he did start to growing fat body regress at a rapid rate - going from adult Kay, to a fat body 12-year-old, to a as fat body three-year-old Toddler, and finally to a big fat Baby. In his infant form, Kay...along with Jay... must find Kima before she becomes too old and dies, and before her father Skon blows up the planet, as he threatens if his daughter is not returned safely i think your rights fat baby agent kay your ready to fights and beat up skon to then your saves me kima i think your surivive is now to then back in mib hq oh yes agent elle puts age machine be your normal age together is now this little girl named kima age your 10 years old and this man that your big fat baby agent kay i think your adulthood with diaper age your 46 years old oh think stellairians leader and his daughter kima lets be walking together today oh yes agent kay your diaper vintage baby hat and black baby gloves oh will that funny moment for that agent jay is yoru crazy time