On the beach, while chasing a crab into a tide pool, Tom finds himself plunged under the sea and transformed into an octopus... And here he is, skillfully and curiously exploring the beauty of the depths. But very quickly, he must face the dangers of the sea and the hostility of some inhabitants... Through a story entirely driven by images where colors explode and details abound, the young reader follows the underwater adventures of Tom-turned-octopus. A dazzling and thrilling immersion!