In the novel Sad Cypress, Horlick is the undergardener on Mrs Welman's estate. After Mrs Welman's death, he remains on to keep the place in order. He is described as being a "tall, good-looking young fellow".
After Hunterbury is sold, Horlick asks Elinor Carlisle to say a word for him to Major Somervell. He hopes that Major Somervell will hire him as head gardener even though he is young, as he had worked under Stephens for four years, and had kept the place well on his own, after the death of Mrs Welman. He hopes to secure the job as he wants to get married that autumn.
On the day of Mary Gerrard's death, Horlick was working in the kitchen garden, from which he was not able to see the house. However, he did notice a car outside the back gate, which he recognises as Dr Lord's car. Dr Lord denies that it was his car.
Horlick later tells Poirot that he is sure that it had been Dr Lord's car at the house that day, as he had noticed the number, MSS 2022. He explains that the car is known in the village, where it is called "Miss Tou-Tou".