Both Sian Lewis’s novels are concerned with friendships and relationships,but here the similarities end.

Plug centres convincingly and attractively on two sixth-formers and their shared activities, jokes and confidences. By experiment, Catrin and Pug find that this closeness can be extended, causing unease for Catrin and fascination for Pug. Pain and terror follow as their ability to “plug” (PugPlug?) into one another telepathically develops.

The storyline will appeal to fans of The X Files, girls in particular. The more experienced reader will more effectively handle the various strands (living alone, parental interference, mother’s boyfriends, father’s desertion) and the slow start. About three-quarters of the way through the pace steps up considerably and the thriller element comes into its own.

Catrin, sensing that Pug’s life is in danger, uses the connection inside their heads to trail her from South Wales to Manchester. This part of the story is gripping despite the confusion that results from the rapid changes of location and introduction of new characters.

The question of the distress which such a gift could cause is not ignored.Finally, both Pug and Catrin opt for autonomy and privacy - they understand what happened, but realise the implications too.

Meanwhile, Lewis evades the deeper issues implicit in The Bath Rat, her novel for younger readers. The notions the story is based on - that rats are intelligent; that an unemployed youth sleeping rough can be full of unrealised potential, and that local councillors and property developers can destroy communities as effectively as the plague which rats used to be feared for - are all quite believable. It is possible, for example, to imagine a rat with human communication skills. (Everat, the hero, can nod, shake his head and raise on eyebrow.)

The laboratory which Everat escapes from is less credible. The experiments at the Martingale Institute involve the inmates in nothing more stressful that having to find their way through mazes in search of strawberries; the worst an animal can expect is to be called names like Vermintrude or Monsewer.

The Humblington Swimming Bath users’ election of the homeless Dylan, who carries “a strong smell of unwashed clothes”, to lead the campaign against the pool’s demolition is similarly hard to believe. Dylan enlists the help of Everat and the sewer rat population then, by a clever sleight of hand, helps the rats to disappear to safety - the Pied Piper (HumblingtonHamelin?) meets Paul Daniels.

As a gentle tale for up to 11-year-olds, it works well. There is entertainment in Everat’s lack of “street cred”, as revealed in the witty banter with other rats such as Doc (who, when asked by Everat if he is a doctor, replies: “As in Martens. Doc Martens, I ate one once, a brown one. The air soles gave me wind”). The rats, such as Charlie with his purple gift-ribbon dreadlocks, are more convincing than the human characters in the book.

The Bath Rat is not as impressive as Sian Lewis’s first novel, Project Kite, which was shortlisted for an Earthworm award, but it offers a lot of scope for classroom activity and could certainly be used as a springboard to further enquiry.