He and Stella boarded a train bound for Pittsburgh, Pennsylvania.
OR
They boarded a train bound for Pittsburgh, Pennsylvania.
The second one because the abbreviation (NKA) is the thing needed in parentheses after the whole title is spelled out
<span>Dr. Lanyon receives a letter from Dr. Jekyll asking him for a favor. The favor <span>involved breaking and entering into Dr. Jekyll’s laboratory and giving some potions to a messenger who will arrive at Dr. Lanyon’s house at midnight.</span></span>