-( Story related, cannot be missed )-
There are six episodes within the third chapter, meaning this might be slightly easier than the previous chapter's story trophy requirement. However, you will find that the missions become a bit more demanding of the level requirement, so be careful of any confrontations against officers unless you match or are above the level suggestion.
Note: You can always send out a Request for help across the online network. Despite the age of the game, you will still find at least a few people willing to hop in and help.