The final instalment in Eileen Merriman’s YA Black Spiral trilogy opens with our desperate voyagers on the banks of a New Zealand lake, near Bethells Beach, in autumn. Though they have outwitted their Spiral Foundation captors yet again, danger for protagonists Violet and Johnno is never far away.

Hesitant in the precariousness of their human forms, at times they continue to shape-shift. They will outsmart immediate threat, or search for each other, in the costume and skin of a wild animal, soaring high, and gliding low, through landscapes and across the world.

Part three finds our protagonists dealing with fall-out. Allies have died and been incapacitated. It is still not clear who one can trust. Family relationships have become strained or broken. The Foundation's shady dealings seem about to be exposed but, if so, this will come at great cost.

This ‘fall-out’ has come about not only through actions and events but also in our characters' growing awareness of the Foundation's misdemeanours. There is little room for emotional reactions towards personal betrayals, for time is too precious and action urgent.

Each of the three books in Merriman’s trilogy hold quite different settings and narrative events. Our characters roam across the world and the adventures that they have in each place are linked to that particular terrain. Their ability to change forms further extends imaginative possibilities. This one reaches into Poland.

As in book two, Black Wolf, Merriman clearly orientates the reader, reminding them of what action has come before. This is not only helpful but necessary as the plot has become ever more complicated with probable consequences for the whole of humanity. Also, like previously, the narrative is told in first person with alternating narrators. Here it is shared between Violet and Johnno, with occasional interruptions by formal records of ‘debriefings.’ Thus, we are privy to their thoughts and worries. Violet, for example, is in "inconvenient condition,” as her pregnancy is termed, and feels extra vulnerable.

The two continue to share dream-flows and think-speak, reading each other's colours and associated moods. Violet interprets Johnno's thought-stream as it is "tinged blue with concern" and he reads hers as it turns "jagged with fright." They must constantly evaluate emotions as they interact in times of greatest stress. At one point, Violet is faced with an ethical dilemma. The reader both empathises with her internal conflict while likewise trying to take a stand. Frequently throughout this series the reader is made to think about how they would react if faced with such conundrums.

Merriman continues to address issues of genetic and technological modification, as our characters find themselves surveyed and controlled by body implants, as well as by the eyes of cameras. She speculates on future inventions, where in this world there are driverless Zubers, underground travellator paths, E-Fidgets and Robo-Vacuums. Most relevantly to a young reader, she covers casual relationships and teen pregnancy without judgement. Violet's impending motherhood at 17 is approached practically by the characters as a normal condition.

Black Spiral has moved past the heady and desperate days of new romance. The focus here is on survival, both for themselves and for the next generations. Plot and character details are ironed out, for example, around earlier drug trial subjects.

Johnno and Violet’s motto at this stage in their journey is, “Together, we are infinite. Alone, we are nothing.” It is only as a team that they can succeed. Merriman has worked her plot details and character development convincingly. In this final, fast-moving instalment, young readers will champion our heroes’ fearless actions, which blaze through as they fight for no less than the survival of unmodified humankind.

 Reviewed by Jessie Neilson