Mont. Code Ann. § 71-1-230

An action to redeem a mortgage of real property, with or without an account of rents and profits, may be brought by the mortgagor or those claiming under the mortgagor against the mortgagee in possession or those claiming under the mortgagee unless the mortgagee in possession or those claiming under the mortgagee have continuously maintained an adverse possession of the mortgaged premises for 10 years after breach of some condition of the mortgage.