As they explored deeper, they came across a large, ancient tree with a door carved into its trunk. Benny said, 'This is the Tree of Secrets, and it's said to hold the key to restoring the garden's vitality.' Mary's curiosity was piqued, and she asked, 'How do we open the door?' Benny replied, 'We need to solve a riddle, and the answer will reveal the door's secret.'