Manila: Solution

First, identify all of the Beatles songs.

One song, "Chains", hints at the next step but is otherwise unused. All of the other song titles can overlap first and/or last words with other songs to make chains of length 2 or 3.

The resulting two- and three-letter strings can then similarly be chained.

These are three of the four herbs from the refrain of Scarborough Fair; the missing link is ROSEMARY.