In a children's market near-dominated by ironic, knowing humour even for the under-10s, Shirley Hughes's suspenseful first novel Hero on a Bicycle (Walker £9.99) will appeal to grumpy parents' nostalgia as much as to every child's desire for a simple wartime adventure story. Set in the summer of 1944, it features 13-year-old Paolo, who lives with his mother and older sister Constanza in the hills outside Florence. Paolo's father, an anti-Fascist, is in hiding, and with the city occupied by Nazis, Paolo's night-time bike rides are a source of hope, adventure and danger.

Another new title, The Abominables (Scholastic £10.99) was also written by an octogenarian, Eva Ibbotson, one of the best-loved children's writers in the world. The story was found among her papers when she died in 2010, and introduces Young Lady Agatha Farlingham, the first person in history to befriend an Abominable Snowman. Lady Agatha ends up raising three Yeti children, Lucy, Clarence and Ambrose, and so it falls to her to rescue her charges from humans who want them for fur coats. Funny and sweet, ideal for reading aloud.

Nostalgia repackaged is likewise the theme of Frank Cottrell Boyce's Chitty Chitty Bang Bang Flies Again (Macmillan £6.99). From the author of Millions and Framed comes this sequel to Ian Fleming's original, endorsed by the Fleming family. In the 21st-century version, Chitty has become a magical flying camper van, and the Tooting family set off for Paris and Cairo, cunningly covering some geography lesson territory en route. Hugely entertaining, innocent fun, and packed with lively illustrations from Joe Berger.

For older children, Annabel Pitcher's My Sister Lives on the Mantelpiece (Orion £6.99), new out in paperback, is an original, warm and subtle exploration of grief. Jamie, 10, lost his sister Rose five years ago and has never cried for her, because he doesn't know how to. Now his mum has run off with the man from the support group, his dad has started drinking, and Jas, Rose's sister, has turned 15 and dyed her hair pink. A complex, beautifully drawn story infused with dry wit.

Kate Saunders's The Whizz Pop Chocolate Shop (Scholastic £6.99)  "chunks of magic in a nutty adventure"  is a rip-roaring adventure story. Oz and Lily's family inherit their great uncle's house. And guess what? The shop beneath used to be a confectioner's, where the world's greatest chocolate-makers once brewed chocolate to make you fall in love, to make you thin, to bring you happiness or hope. No wonder someone's after their secret recipes. Magical and inventive fun.

Saving the funniest and the best till last, Barry Loser: I Am Not a Loser (Jelly Pie £5.99) is from the Mr Gum school of writing and illustrating: hugely enjoyable, surreal chaos from the notebooks of Barry Loser, the schoolboy anti-hero desperate to take revenge on crocodile-faced creep Darren Darrenofski. The review of the eight-year-old boy in our house who devoured it in two days? "Can I keep it to give to a friend?" Best recommendation you can get.

There's an essay to be written on the significance of the bicycle in Italian culture. From Vittorio de Sica's film Bicycle Thieves and the Roman urchins of Pier Paolo Pasolini's writings to Niccolò Ammaniti's I'm Not Scared, this humble form of transport brought new freedom to the disadvantaged, from the peasant and artisan to the child.

In Hero on a Bicycle, Paolo's relationship with his bike is as important to him as that with his faithful old dog, and both have a role to play in Shirley Hughes's first novel. It's set in a place and period little written about outside Italy: Florence during the German occupation of 1943/4. Thirteen-year-old Paolo sets out each night on his bike for the city centre, believing his excursions to be a secret. But his mother and older sister Costanza know all about them, and are wearily waiting for his safe return so that they can sleep.

What none of them knows is where Paolo's father is; his political views have put him in danger from the fascists and he has had to go into hiding. Meanwhile the hills are full of partisans waiting for the moment when the allies will arrive to liberate the city. The increasingly desperate Germans are a danger to all they believe to be part of the resistance.

Into this heady mix are introduced two escaped allied prisoners, a Brit and a Canadian; the partisans have decided that Paolo's mother should hide them until they can be safely smuggled out of the city and back to their units. Tense scenes follow as the Gestapo come to search the house, a villa in the hills south of Florence.

Paolo's mother is English and can speak to the prisoners. English David is captured trying to escape into the city and Joe the Canadian is wounded. Only Paolo's fierce courage  and his bike  get Joe back to the villa, where the dangerous game of hide and seek continues, sweetened by a developing romance between the prisoner and Costanza.

I fear that a lot will be made of Hughes publishing a first novel in her 80s. If you think about it, though, she has been telling us stories for 50 years; this is just a logical progression. The illustrations here are limited to small black and white chapterheads but you can find more by the author-artist at www.heroonabicycle.co.uk.

It is a story that Hughes has wanted to write for years, as the foreword tells us, based on her experiences at the age of 19, and on people she knew in Italy just after the war, where partisans still gathered in the piazzas to sing "Bella, Ciao!" only a few years after killing collaborators.

The book has a deliberately retro feel, which I hope won't put young readers off. The font size and the protagonist's age suggest a readership of nine or 10 but the language  excuse the pun  takes no prisoners, and there is a higher proportion of exposition to dialogue than this age group has come to expect.

But it's an exciting story, well told, by someone with a strong feeling for the time and place. I hope it finds the right readers in today's crowded market. Any girl or boy who has ever gone freewheeling down a hill towards an unknown adventure should be among them.

 Mary Hoffman's David is published by Bloomsbury.