Lyoshka Vostretsov is the most ordinary boy of our time. He is not very brave, and he has no friends at all. One day an incredible incident happens in his life - a real balloon flies onto the balcony. A mysterious guest is hiding in his basket - the frog Trum. This creature is a secret agent from the magical country of Quagmire who escaped from captivity. Thrum tells the boy about the Solar Queen, with whom his country has been at war for a thousand years. To stop the senseless war, the frog needs help. Lyoshka agrees to help, not fully understanding what exactly the frog is up to, and what price he will have to pay for a dangerous adventure. Amazing adventures, difficult moral choices and a meeting with a true friend await him.