Martin has a mosquito bite, from which he is suffering from symsymsympatheticus. This is an affliction where the next person bitten by the mosquito has a bit of Martin residue in him/her, and Martin is feeling everything that next person is feeling. But what if the next person isn't a person, but a horse? It ends up being not only a horse, but a race horse named Sweet Sister, who is running better than ever.