Complex sentence: IMDB.com, accessed June 8,2011 It is the only screen or television version that retained the operetta's primary plot (the orphans' escape from their cruel uncle), but it omits the secondary plot involving the nursery-rhyme characters.
Split into simpler sentences: IMDB.com, accessed June 8,2011 It is the only screen or television version which retained the operetta's original primary plot (the orphans' escape from their cruel uncle). Hoewever, it entirely omits the secondary plot involving the nursery-rhyme characters.