Joaquin is having a hard day at school. He struggles to speak up in class even though he knows the answers, he doesn't feel included when trying to play soccer with his friends, and he ends up sitting alone during recess—feeling invisible.

But when he investigates a strange shimmery light by the playground slide, he is transported to a special forest filled with fantastical creatures known as alebrijes, or magic companion animals.

His friend, Imogen, introduces Joaquin to several alebrijes, and the special creatures share the ways they help people manage their emotions. One creature roars like a lion with Imogen when she feels angry and needs to let it out. Another one helps Noemi blend into the background like a chameleon when she is feeling nervous and needs a moment to herself. A third alebrije has big ears to hear all of Tío Andres's worries.

Joaquin learns how to identify his needs and create an alebrije specifically for him, and when he returns to school, he is no longer feeling alone or invisible. With his new, fantastical friend helping him, Joaquin's hard day is now one of his best yet.