Afather sits with his three children — ages 7, 9 and 12 — as they illustrate a homemade picture book that he wrote for them. The book, “Journey to Galumphagos,” focuses on Emily, a lonely girl who reacts to her outcast status at school by persuading her younger sister and brother to escape with her to the sumptuous island of Galumphagos. But the island is not quite the tropical paradise they envisioned. Massive, antagonistic creatures called Galumphers live there. The kids escape the island …