Rex is a Bioform, a dog-like killing machine sent out to obey his master's orders because he is a Good Boy. But when he is freed from the innate need to listen to a master, he must decide on his own who is the enemy, and who must be killed.
Another excellent sci-fi from Tchaikovsky that's quite "out there" in terms of its concept. Also very cute because there are dogs involved (albeit murderous ones).