In Horrid Henry's Gross Day Out, Henry is a mischievous young boy who loves nothing more than sitting on his sofa and watching his favorite show, Gross Class Zero. However, when a freak accident in a science laboratory brings the characters from the show to life, Henry's world is turned upside down. Suddenly, he finds himself face to face with his gross and slimy heroes, and their misadventures bring chaos and excitement to his mundane day. As the day wears on, Henry and his animated friends find themselves embroiled in an epic battle against their nemesis, Miss Battle-Axe. Through it all, Henry learns the importance of teamwork and realizes that sometimes, the most unexpected adventures can turn out to be the most fun and rewarding. With plenty of humor, action, and gross-out gags, Horrid Henry's Gross Day Out is a fun-filled family adventure that's sure to keep viewers of all ages entertained.