Ontario, 1904. A blood-spattered, semi-feral boy staggers out of the forest, with no memory (he says) of the events that gave rise to his desperate state. He is lucky enough to stumble upon 16-year-old Emmy who, as daughter of a pioneering female doctor, is free of the small-town prejudices of the other locals. For Astor, Ontario is not the world’s most tolerant spot and inhabitants need reminding about their biblical obligation to welcome the stranger.

Stranger, by JC features editor Keren David (Atom, £7.99) is a breathtaking murder-mystery but also much more. As Emmy sets out to investigate and to rehabilitate the boy, her story is interwoven with that of Megan, visiting the same town in 1994 for her great-grandmother’s 105th birthday. Megan is nursing her own secret sorrow — her story is seen only in small glimpses but touches a real emotional chord.

This is a double coming-of-age novel and David creates a strong sense that Emmy’s and Megan’s experiences and the choices they face are part of a wider feminist destiny.

Astor’s newspaper also has a central role in the plot, with now-quaint-seeming concepts such as microfiche being introduced to the 21st-century reader and bringing touches of humour. Age 12 up.

The historical adventures continue in Matt Killeen’s Orphan Monster Spy (Usborne, £7.99).

After a failed escape from 1939 Germany, in which her actress mother is killed, Sarah meets a mysterious Englishman, also on the run. He transforms the Jewish teenager into an undercover agent, renaming her Ursula.

To this job, she brings her athletic skills as a once-promising gymnast; a flair for acting, piano and languages (stage-trained by her mother) — and the daring to infiltrate a Napola (Nazi elite school), with its brutal hierarchy of bullying. Age 12 up.

The Spy Who Played Baseball is the story of Moe Berg, a real-life major-league baseball player of the 1930s. Carrie Jones’s picture book (Kar-Ben, £5.69) tells the story of this quietly brilliant man, who studied at Princeton and would exchange tactical remarks with his college team mates in Latin during baseball games.

Like Sarah, a talented linguist, he was enlisted as a spy in the Second World War and was sent to gather intelligence about German progress in atomic weaponry. Age seven to nine.