Leah Kolbe, an antique dealer in Hong Kong, is packing many of her antiques to be sent to London because of the possible invasion by the Japanese. She is soon to marry Jonathan Hawdyne, a lawyer and member of the British defense force.

When the Japanese attack Hong Kong Jonathan is sent into battle, and his fate is unknown when Hong Kong surrenders. Leah manages to escape to Macao with nothing but the clothes on her back.  She obtains work in the British Consulate, and is there recruited by Intelligence to get close to a Japanese businessman, the son of an ammunition manufacturer, to spy and get information for the British.  With great anguish she becomes the man's mistress.  She learns that Jonathan is now a prisoner of war.

When the war is over they must try to reconcile the past.

Deep Night presents an excellent picture of the conflict in Hong Kong and the area during the Japanese invasion.  The streets of Hong Kong and Macao during this tempestuous period are vividly portrayed.   Leah's anguish and dilemma during her travails is described in detail.