WARTIME FRANCE, 1944

Trust absolutely no one.

This is the only advice newly recruited SOE agent Elisabeth Shepherd is given when faced with the impossible.

Her mission: to enter Nazi-occupied France and monitor the Germans' deadly long-range missiles.

GUILDFORD, 2018

Betty is celebrating her 100th birthday when she receives an invite from the Century Society to reminisce on the past.

She remains mysteriously tight-lipped about her past, however.

And then her carer, Tali, discovers a box full of maps, letters and a gun . . .