“The Mermaid: Lake Of The Dead” (*1/2 out of four) was a stultifying horror thriller about a young woman (Viktoria Agalakova) who drowned a few centuries earlier who is reborn as a mermaid and has to overcome her fear of the dark waters to combat monsters and not become one herself; elsewhere, an evil mermaid (Sofia Shidlovskaya) falls in love with the fiance of the good mermaid and tries to keep them apart which leads to things getting really ugly in them thar waters. Or something like that. Both inept and inert and loaded with howlingly serious dramatics. This is strictly for anyone who thought “Aquaman” was too serious and needed to be lightened up.