“12 Desperate Hours” (** out of four) was a perfunctory suspense melodrama about an overworked mother (Samatha Mathis) who finds herself and her children under siege in their own home when a murderer (Harrison Thomas) invades their house and threatens them all. Obvious rip-off of “Desperate Hours” right down to its title with little suspense or character development and thus not much to keep you involved. It’s nice to see Mathis on screen again but she can’t do much to enrich this tired material. Inauspicious directing debut for actress Gina Gershon.