The Under the Bed Grinner. Jitter Jumpers, #12

Eleven-year-old Giselle lives for the daylight, a world of buttercup-yellow walls and sun-drenched sanctuary. But when the sun sets, her room transforms into a "tapestry of brittle, shadowed strands." The "Under-The-Bed Grinner", a spectral entity with an unnerving emerald glow, has arrived. Giselle must discover if the Grinner is a literal monster or a "Psychosomatic Phantom" born from her own deepest fears.
In the darkness, the lines between "self and other" begin to blur, and Giselle must find the strength to face the grin before it swallows her whole.