According to the Elements...

I was revising my first novel for submission, and I added the sentence: "Since I can’t borrow Harry Potter’s invisibility cloak or slip on Bilbo Baggins’[s] ring, I bow my head to avoid eye contact..."

When I reread the sentence I started wondering if the ring that Bilbo Baggins owns needs to be shown as a possessive with an extra  s  or just an apostrophe after the  s  in Bilbo’s last name. To find my solution, I searched the internet and found conflicting answers. 

Microsoft Word advised me that Baggins’s was incorrect, and when I removed the  s after the apostrophe, MSWord removed the ugly red underline under Baggins'. 

Even more perplexed than when I started, I consulted with good ole’ William Strunk and & E.B. White in the book The Elements of Style. Right there on the first page, rule one says:

“Form the possessive singular of nouns by adding 's. Follow this rule whatever the final consonant.”

Hmmm... whatever the final consonant? That means, a noun or proper noun that ends in  s  must be followed by 's  when writing the possessive object to follow. Thus, my sentence should read Bilbo Baggins’s  ring. 

I could have avoided everything if I would have deleted Bilbo’s sir name entirely, but what then would I have learned?