Of Toys & Portals by Clifford Mailou

Recovering after 12 months in a trauma-induced coma, Marcus Collington remains deeply disturbed. To avoid therapy and preserve a life in shadow he makes technical self-help videos on the internet.
One day a trio of strangers claiming to be makers of sophisticated toys call unexpectedly to canvas his help in constructing a problematic mechanism. Bewildered and unsettled, he seeks solace in a late night coffee shop.
While puzzling over the group's schematics, the server adds to his mounting confusion by handing him a cryptic note: a message from a striking ‘Amazonian’ woman he failed to notice as she left moments before.
This woman and her daughter are destined to distort his future beyond recognition.
Despite all reason Marcus finds himself irrevocably drawn into the sphere of the three toymakers mesmerised, in particular, by one of its members – the intoxicating Katie.
By degrees the incredible truth is revealed.
All three were coma patients on a sister world. In a failed experiment conducted my an eminent professor, their consciousnesses were unintentionally released, sucked through an interdimensional portal and connected to the minds of three coma patients on this side of the divide. Upon waking, the hosts, unharmed but still 'sleeping', became ‘piloted’ by the visitors.
Marcus soon realises that his own recovery was no fickle quirk of fate. There were other 'travellers', the professor among them, who, it transpires, attempted to merge with him. In his case, however, the process did not complete, leaving Marcus harboring only fractured, lingering remnants of the scientist’s brilliant mind. Locked inside him there may be vital information the visitors need to complete a transference device they have been secretly assembling.
Time, however, becomes a relentless enemy.
In the midst of turmoil lost secrets come to light offering a glimmer of hope, but a fatal illness stalks the travellers. Can they return home in time to save themselves? In fact will that save them?
A frantic race begins. Can Marcus unlock the secrets in his mind before the critical tether that links both worlds collapses forever?