He was completely engrossed in the short story he was reading.
The preface to the story had explained that the writer had been high on some drug or other when he wrote it. The story involved a young man staggering along a city street late one night looking for a taxi. It described how the writer had based the idea on a time when he was high on some drug or other when on holiday in Ibiza, a city known for its vibrant nightlife, a popular destination for partygoers from all corners of the globe and often referred to as the party island. It happened at a time when he had stumbled out of a night club, being high on some drug or other, and found a man wandering around in a haze, apparently high on some drug or other, trying to find a taxi.
Apparently, at the time of the incident, despite being high on some drug or other, he had returned to his hotel to write a story based on the event.
Reading this story with great interest, despite himself being quite high on some drug or other, he found it engrossing.