Here the 1907 LDS vest-pocket edition omitted the definite article the before the word prison, probably because in English the word prison typically lacks the definite article in prepositional phrases (thus “into prison”, “in prison”, and “out of prison”). As discussed under Mosiah 7:8, the Book of Mormon text uses the when referring to a specific prison, as is generally the case here in Alma 14:
The 1907 edition was not used as a copytext for subsequent LDS editions; thus the reading with the missing the was not transmitted. The critical text will retain the original “out of the prison” here in Alma 14:28.
Summary: Maintain in Alma 14:28 the use of the before prison, the reading of the earliest textual sources; such usage is expected here in Alma 14 since a specific prison is being referred to.