When Ms. O has bizarre side effects after being sprayed by a weird plant, Olive and Otto must travel around town finding the correct measurements of the ingredients for the medicine to cure her, all while keeping Ms. O's condition a secret from her. The only thing that can bring Ms. O’s old partner O’Donahue out of retirement is the very thing that put him there in the first place: a mysterious villain and a case that’s gone unsolved for years.