The Icarus Girl by Helen Oyeyemi

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I know a cheeky five-year-old who always knows where to pin the blame. Whenever trouble comes along, it is never her fault; Tallulah is always the culprit. In Tallulah, she has refined the notion of imaginary friend to that of imaginary scapegoat.

This, at first, seems to be exactly the sort of brouhaha that, in Helen Oyeyemi's first novel, clusters around eight-year-old Jessamy Harrison: a precociously bright but stutteringly shy girl with a placid English dad and feisty Nigerian mum. Jess has always had difficulty fitting into any group of friends, and has long inhabited a nagging sense of imbalance or incompleteness. She suffers severe frights, and plagues parents and teachers with tantrums and bouts of hysterical screaming, which amplify her peer isolation.

When TillyTilly, an impish Nigerian girl, attaches herself to Jess's hollow existence, Jess feels strengthened. She is soon forced to accept that TillyTilly is not real - at least, not within the physical world. Neither is she "the kind of imaginary friend that you'd mistakenly sit on" in the classroom. She is an über-Tallulah, invisible to all but Jess and with a routine ghostly cold presence, provoking incidents in the real world for which Jessamy scoops the blame.

TillyTilly first appeared during a holiday at Jessamy's mum's family compound in Nigeria. She is a waif-like figure attracted to Jessamy's lonely neediness. Her powers are surreal: inhabiting a spooky old house, magically opening locked doors, remaining invisible to adults. Back in England, TillyTilly resurfaces with more sinister intent, cloaking Jessamy's passage into other houses, smashing a computer and a mirror, causing Jessamy's dad to collapse.

TillyTilly reveals to Jess the image of Fern, a stillborn twin sister whom both parents had hushed up. This shocking information is a fulcrum, tipping the latter half of The Icarus Girl into psychological free-fall as TillyTilly, cohering more and more as the twin's emergent spirit, grapples for possession of Jessamy's life.

Jessamy lives in three worlds, her mum wails: physical, spiritual and the Bush (a sort of "wilderness of the mind"). Coupled to her half-Nigerian and twin status, this makes for a complex matrix of identity confusion which Oyeyemi handles fairly well.

The early, and rather fey, schoolgirl-ish episodes suggest the author's sentimental attachment to a magical realism which gently encourages the possibility of TillyTilly being an alter ego, a willful delusion or a symptom of madness. As TillyTilly punches her way more defiantly into the physical world, however, Oyeyemi deftly ratchets up the anxiety to give a sharply chilling mystical story that owes as much to Freddy Kruger as Ben Okri.

This is a strong début from a 20-year-old who squeezed her writing in around her A-levels. Oyeyemi is able to modulate from the skittish internal landscape of an unbalanced child to an altogether more menacing psychological pursuit with a confident voice. An immature subject interfacing with the paranormal is no easy platform for the demonstration of a writer's early maturity, but The Icarus Girl delivers well and promises more.