Like the cyberspace explored by its heroine Mara, Exodus by Julie Bertagna (Macmillan Children’s Books, pound;9.99) teems with ideas. Extended from a short story published in Phenomenal Future Stories, a collection edited by Tony Bradman (Corgi, pound;4.99), it combines environmental fable and futuristic dystopia with a tale of courage and survival, set at the beginning of the 22nd century. Sea levels have risen drastically and at the novel’s opening a desperate, storm-battered island community is forced to take to the open sea in boats, leaving its elders to drown. Arriving at the modern city constructed above Glasgow (here the story’s logic escapes me - wouldn’t Ben Nevis and the other Munroes be more obvious destinations?) the survivors find themselves refused admittance and facing starvation.

The resourceful Mara discovers other groups of survivors - the Sea-Urchins and the Treenesters. The latter hail her as their saviour, the “Face in the Stone”, and reluctantly Mara accepts the role. Reconnoitring the streamlined, self-contained city interior, she meets an ally in the grandson of one of the founders and persuades him to reject a society that protects its citizens, but exploits its underclass as slaves and condemns others to perdition.

Bertagna’s world is vivid and colourfully populated and she doesn’t allow Mara to achieve heroine status without facing the realisation that she, too, could be ruthless enough to sacrifice some of her dependants in order to save others. And the question posed by this absorbing novel could hardly be more important: how is life on Earth to be sustained in an uncertain future?

In Starseeker, Tim Bowler’s compelling new novel (Oxford University Press, pound;10.99), survival is in a more localised context. Luke, a troubled 14-year-old with a prodigious musical talent, has become brooding and withdrawn since the death of his father, a concert pianist. Dismayed by the prospect of a new partner for his mother, he vents his anger on her and other adults and associates with village thugs. Dares and threats impel him to break into the house of a “repulsive” old woman, where his life is complicated by a tearful blind girl locked in an upstairs room and whose trust in Luke poses new dilemmas. As well as his father’s musical gift, Luke has inherited an extra sensibility, the ability to hear sounds imperceptible to others and to hear music in terms of colour and texture - this strand is the most lyrically-written.

Although the plot strains towards the end, this is a thoroughly engrossing story which involves the reader fully in Luke’s journey towards acceptance of his father’s death and appreciation of his own gifts. It’s long enough to feel spacious and developed, and the reader is compelled to turn the page.

After the richness of Starseeker, Margaret Haddix’s Amongst the Betrayed (Red Fox, pound;4.99) feels thin and sketchy. I enjoyed Amongst the Hidden (Red Fox, pound;4.99), the first book in The Shadow Children sequence, but found this, the third book, disappointing. It continues a story set in the near future, where families are allowed only two children and third children must stay hidden or risk execution. Focusing on Nina, an “illegal” who’s imprisoned and invited to betray others, the novel does raise questions about personal survival and responsibility for others, but neither the characters nor the settings are drawn enough to satisfy.

The Edge (Orion Children’s Books, pound;4.99) in the title of Alan Gibbons’ book is a shoulder of moorland near the northern town where Danny and his mother seek refuge; it’s the tough estate where his grandparents live and it’s also the determination which keeps Danny fighting when the odds are stacked against him. His mother’s brutal, obsessive boyfriend is determined to track her down, mixed-race Danny meets prejudice and hostility from his stubborn grandfather and, more dangerously, from bullies on the estate. Characters and settings are simply-drawn and the short sections, from various viewpoints, encourage page-turning. Gibbons has written a pacy novel with immediate appeal for boys and girls.