The cast from the Rugrats - adults Stu (voice of JACK RILEY) and Didi Pickles (voice of MELANIE CHARTOFF); Charlotte (voice of TRESS MacNEILLE) and Drew Pickles (voice of MICHAEL BELL); and Betty (voice of KATH SOUCIE) and Howard DeVille (voice of PHIL PROCTOR), along with kids
Chuckie (voice of NANCY CARTWRIGHT), Angelica (voice of CHERYL CHASE), Tommy (voice of E.G. DAILY), Phil and Lil Deville (voice of KATH SOUCIE), Susie Carmichael (voice of CREE SUMMER) and Dil Pickles (voice of TARA STRONG) - are set to go on a cruise accompanied by the Pickles' pet dog, Spike (voice of BRUCE WILLIS).
Little do the rest know that Stu has arranged to captain them on a small boat rather than have them board a luxury ocean liner. After setting sail, it's not long before they capsize and end up marooned on an apparently deserted isle.
They're not alone, however, as the cast from The Wild Thornberrys - adults Nigel (voice of TIM CURRY) and Marianne (voice of JODI CARLISLE), teenager Debbie (voice of DANIELLE HARRIS), 12-year-old Eliza (voice of LACEY CHABERT) and wild younger brother Donnie (voice of FLEA), along with Eliza's primate friend, Darwin (TOM KANE) - are also there. It seems that Nigel and Marianne are trying to find an elusive leopard, much to the chagrin of their kids.
When various members of the Rugrats meet their counterparts in the Thornberrys, all sorts of bedlam breaks out.