Unicorn boy

"The first few years of Brian Reyes' life were unremarkable--nothing weird about this kid, no sir. Then, one day, a bump appeared on his head, and it grew . . . and grew . . . and grew until it was a full-blown, sparkling, singing unicorn horn. That's absolutely the last thing a shy kid like Brian wants, but destiny waits for no unicorn boy. Luckily, Brian has his reassuring pal Avery to keep him grounded as weird occurrences start stacking up. . . . But when shadowy creatures from another realm kidnap Avery, Brian has to embrace his fate to rescue his best friend"--Provided by publisher.