Maryland Code, Real Property § 14-108

(a) Any person in actual peaceable possession of property, or, if the property is vacant and unoccupied, in constructive and peaceable possession of it, either under color of title or claim of right by reason of the person or the person's predecessor's adverse possession for the statutory period, when the person's title to the property is denied or disputed, or when any other person claims, of record or otherwise to own the property, or any part of it, or to hold any lien encumbrance on it, regardless of whether or not the hostile outstanding claim is being actively asserted, and if an action at law or proceeding in equity is not pending to enforce or test the validity of the title, lien, encumbrance, or other adverse claim, the person may maintain a suit in accordance with Subtitle 6 of this title in the circuit court for the county where the property or any part of the property is located to quiet or remove any cloud from the title, or determine any adverse claim.

(b) The proceeding shall be deemed in rem or quasi in rem so long as the only relief sought is a decree that the plaintiff has absolute ownership and the right of disposition of the property, and an injunction against the assertion by the person named as the party defendant, of the person's claim by any action at law or otherwise. Any person who appears of record, or claims to have a hostile outstanding right, shall be made a defendant in the proceedings.