Useless and the Mandala Trap. A Useless Series, #1

Ewen "Useless" Euston has the worst nickname in his neighbourhood. When a sprained ankle keeps him home from a mysterious rally at the park, he watches helplessly as every child in the district, including his twin sisters, vanishes into thin air. No one else seems to notice. Parents have forgotten their own children exist. Following an old Labrador through a swirling pattern on the oval, Ewen stumbles into another world entirely.
The missing children are here, drugged to forget their real lives, forced to work as labourers for strangers who want to keep them forever. The gateway home won't stay open long. Armed with nothing but his wits and a few unlikely allies, Ewen must find a way to free the children before the gate seals shut, and he loses everyone he loves. For readers 10+ who love brave underdogs and parallel-world escapades.