Agatha was 38 years old and in Istanbul...

In April 1928, Agatha Christie's divorce from her first husband Archie Christie was finalised. Agatha was ready for a holiday, and began planning a trip to the West Indies. But a chance meeting with a young naval officer and his wife just returned from the Middle East changed her mind, and she decided upon Baghdad instead. She was 38 years old. Agatha's journey began at Victoria Station in London, from where she travelled to Calais. There she transferred to the Orient Express, which took her all the way to Istanbul. The train route from Calais to Istanbul [1] covered 3342 kilometres and lasted three days.
Mavi Boncuk |

... undoubtedly, my favourite train. I like its tempo... Allegro con fuoco, swaying, and rattling and hurling one from side to side in its mad haste to leave Calais and the Occident.

... All my life I had wanted to go on the Orient Express. When I had travelled to France or Spain or Italy, the Orient Express had often been standing at Calais, and I had longed to climb up into it. Simplon-Orient-Express--Milan, Belgrade, Stamboul...
Agatha Christie, Come, Tell Me How You Live (1946)

... There was a subtle difference on passing from Europe into Asia. It was as though time had less meaning. The train ambled on its way, running by the side of the Sea of Marmora, and climbing mountains...
Agatha Christie, An Autobiography (1977)

[1] Istanbul and Pera Palas Hotel, had a very special place in the life of best-selling author Agatha Christie. She stayed in the hotel many times between 1926 and 1932, and one of her best-known stories, Orient Express, was written there.