Questions & Answers about Vakten følger fangen.
In Norwegian, the definite article is usually added to the end of the noun instead of being a separate word.
So:
vakt = guard
vakten = the guard
fange = prisoner
fangen = the prisoner
The ending -en here marks singular definite for these nouns.
The dictionary forms are:
vakt = guard
fange = prisoner
Their indefinite forms are:
en vakt = a guard
en fange = a prisoner
Their definite forms are:
vakten = the guard
fangen = the prisoner
Both nouns are normally treated as common gender nouns in Bokmål, so they take en in the singular.
Følge is the infinitive form, like to follow in English.
Følger is the present tense form, meaning follow/follows.
So:
å følge = to follow
følger = follow / follows
In this sentence, the action is happening in the present, so følger is the correct form.