Ruta Sepetys and Steve Sheinkin’s nov­el for mid­dle-grade to young adult read­ers is sus­pense­ful and his­tor­i­cal­ly accu­rate. Set in Eng­land in 1940 among char­ac­ters relat­ed to the top-secret Bletch­ley Park cryp­tog­ra­phy cen­ter, it illu­mi­nates the intense efforts to break the Ger­man Enig­ma code.

At the same time, sib­lings Lizzie and Jakob Novis are ded­i­cat­ed to unrav­el­ing the mys­tery of their per­son­al loss. World War II has caused the dis­ap­pear­ance of their moth­er, who appar­ent­ly under­took a diplo­mat­ic mis­sion in Poland right before the Nazi inva­sion of that coun­try. Now the sib­lings are some­times at odds with one anoth­er. While Jakob accepts their mother’s death as a fact, Lizzie refus­es to over­look oth­er pos­si­bil­i­ties for her fate. 

Sis­ter and broth­er are out­siders in British soci­ety. Their mater­nal grand­moth­er is Amer­i­can, and their late father was Jew­ish. Amer­i­ca has not yet entered the war, and Gran is safe, liv­ing in ​“a posh place called Cleve­land.” She wants her four­teen-year-old grand­daugh­ter to join her. Jakob is a young adult who has inher­it­ed his father’s ana­lyt­i­cal skills, and fol­lows the career of his Amer­i­can hero, Jew­ish ball play­er Hank Green­berg. Lizzie is bold and per­sis­tent; Jakob is reserved and focused on the details of his urgent work at Bletch­ley Park. The affec­tion between broth­er and sis­ter, and the con­flicts that divide them, dri­ve the nar­ra­tive as much as Britain’s race against time to break the Ger­mans’ code.

A cast of sec­ondary char­ac­ters pro­vides a back­drop to the sto­ry. Rather than depict­ing the British as mere stereo­types of hero­ic resis­tance, they offer a com­plex range of per­son­al­i­ties and moti­va­tions. Some are his­tor­i­cal fig­ures: Alan Tur­ing and Joseph Kennedy make appear­ances. Turing’s leg­endary genius is implic­it, and his human­i­ty emerges in qui­et con­ver­sa­tions with Jakob. His quirky choice to bury sil­ver ingots in the woods near Bletch­ley is inte­grat­ed into the plot. Kennedy, then ambas­sador to the UK, was pres­sured to resign by Franklin Roo­sevelt because of his unabashed Ger­man appease­ment. Kennedy’s cameo role in the nov­el high­lights his untrust­wor­thy personality. 

There are sev­er­al key female char­ac­ters who, while fic­tion­al, are based on the doc­u­ment­ed real­i­ty of female rep­re­sen­ta­tion in the code-break­ing estab­lish­ment. (In their after­word, the authors explain the novel’s his­tor­i­cal back­ground.) Oth­ers who inter­act with Lizzie and Jakob grant a cin­e­mat­ic breadth to the sto­ry, act­ing as both sup­port­ers and foils. Col­in, whose fam­i­ly owns the humor­ous­ly-named Shoul­der of Mut­ton Inn, is Jakob’s under­stand­ing friend and Lizzie’s poten­tial roman­tic inter­est. Mar­i­on Hoff­man, a Jew­ish refugee from Vien­na, also works at Bletch­ley. She devel­ops a bond with Lizzie and adds some sur­pris­ing ele­ments to the adven­ture. Cre­ative uses of font to sim­u­late doc­u­ments, and full pages of his­tor­i­cal pho­tographs are inter­spersed through­out, adding to the sense of immer­sion in the World War II era.

There are many rid­dles to deci­pher at Bletch­ley. Lizzie and Jakob are called upon to use both intel­lec­tu­al and emo­tion­al resources to resolve them, and read­ers of this inven­tive, high­ly rec­om­mend­ed nov­el will feel ful­ly immersed in the sib­lings’ experiences.