Max, Becky and their Mum, go to stay at their Grandpa’s house. Max and Becky know their Grandpa is a famous writer, but they don’t know he is like a method actor, who acts out the lead character of his stories to write the story better. The kids discover his latest book, but think it is his diary, and that he has met a vampire who has bitten him. Worried for him, they go to the library to look up books on vampires, and meet two gothic kids, Charlotte and Jacob, who claim to know all about vampires. They tell Max and Becky that the only way to save their Grandpa, is to kill the head vampire that bit him, or if it is too late, Grandpa himself, to save his soul, but first they will have to test Grandpa to see if he’s a vampire.
Grandpa notices the kids looking at him differently, and realizes that he is fooling the kids with his method acting. He tells his drama coach girlfriend, Monique De Lupont and she wants to see it all first hand and join in. At a dinner party she has an allergic reaction to the garlic, which she is really allergic to, and ends up going to hospital. This convinces the kids that their Grandpa is a real vampire and that she turned him into one. Max and Becky get coached by Charlotte and Jacob, on how to catch and stake vampires. They hatch a plan to catch Grandpa and his girlfriend. Will Max and Becky save their Grandpa by killing the vampire that bit him or will they have to kill Grandpa? Will Grandpa survive long enough to tell them he’s only pretending to be a vampire for his book?