A mad scientist grandfather invents a genetic transformation machine and his 4 year old grandson accidentally turns his body into that of a 30 year old man. Baby Bobby escapes and runs around town as his siblings try to catch him before their parents get back from vacation AND before the bad guys get to him first. The machine is worth a lot of money and they only have a day before the machine loses its capabilities to change baby bobby back.

　　鬼子的飛機炸死了去鎮(zhèn)上賣魚的爹媽。那年，姐姐大荷花十四歲，弟弟小荷花十一歲。爹媽死后，大荷花擔負起照顧弟弟。弟弟逢人就問：“鬼子為啥炸死我爹媽”，沒有人能回答他。姐弟倆開始以自己的方式復仇。