Search for the 4th kid is the 29th episode of Super Digimon Xros Wars.
Ian begins to think and tells Patamon and Flamemon that Jeri might be the 4th kid. Jeri then comes by and Ian puts Flamemon and Patamon in the X Loader then Jeri asks about it puts her hand on it and it begins to glow yellow and Angelmon tells them that she is the 4th kid. CeCe then comes by with Poromon. Ian then comes up with a plan and hides Jeri with CeCe to make sure the Dark Knight Army won't find her. Ian the Digi-Xroses Dorulumon with Nefertimon as a guard, and Ian then Digi-Xroses Flamemon and Sparrowmon, then BlackSparrowmon and DeadlyAxemon attack (after Ian left to find Maria) after some fighting Jeri gives up and tells them what they want to know and is kidnapped. Maria then contacts Ian about the problem. Ian the chooses to hurry.
(Numbers indicate order of appearance. Bolded characters are fought by the protagonists, and italicized characters appear only as a voice or silhouette.)