His intention is to spend some weeks fishing the glen, but he discovers on arriving that he has carried away a newspaper on which is scribbled a poem, "The beasts that talk, The streams that stand, The stones that walk, The singing sand…That guard the way To paradise".
A newspaper advert asking if anyone can identify the lines of the poem brings in a pilot colleague of Bill Kenrick, the dead man, which eventually provides the clarifying clue.
Having been blown off-course by a dust storm over the Rub' al Khali (the Empty Quarter of the southern Arabian desert), Kenrick had discovered the location of the legendary lost city of Wabar.
Being a vain man, Heron Lloyd wished to keep the glory of the city's identification for himself and had accordingly murdered Kenrick on the train and so arranged his death that it appeared accidental.
[1] Adapted by Bertram Parnaby, it was later broadcast in 1956 for BBC Home Service's "Saturday Night Theatre"[2] and televised in 1969 in an episode of the "Detective" series that is now missing.