Maddie arrives at the maze, along with Ursula. She asks her grandma if she knows anything about the journal she found. Ursula seems surprised and sentimental - it was Charlie's most treasured possession. How did Maddie get it? Maddie starts to tell her that Charlie called and sent her on the quest, but Ursula interrupts, annoyed. That can't have been Charlie! She leaves, and Maddie decides to get to work.
Maddie looks at a drawing in the book as Julius arrives. She asks him if he knows what it is, but he doesn't. He tells her a bit about knowing her grandpa Charlie when they were younger. He says he was keen to be an inventor and prove himself as a Boulton. Maddie decides to try and build what the drawing depicts.
Maddie wonders why Charlie thought this book would help her. She scours through it and finds that there are little codes and things. Julius, still there, tells Maddie that it's no wonder the book is filled with clues - Charlie loved them! He's not sure why, but they were his bag. The dog is there too and makes Julius sneezy.
Deb arrives and Julius is surprised to see her, and seems a little embarrassed. Rufus is still there, Julius is sneezy but Deb says he's just super emotional that she's home. She's loud and proud, flirts with Julius and scares him away.
Deb chats to Maddie. It's been a while since they saw each other but there's clearly affection. She asks what Maddie's doing in the old maze, and Maddie says she's trying to help Grandma. Deb says that's why she's home, too. Where is that sister of hers??
Ursula arrives and doesn't seem happy to see Deb. She says she doesn't need help, and can manage on her own. Maddie asks if either of them can help her - why did grandpa write so many codes! Deb has no idea, but Ursula smiles, and says she knows the reason.
Ursula reveals that Charlie's mom was a codebreaker in WWII! She had to keep her job secret. Maddie thinks it's amazing, and Ursula agrees. Charlie's mom was formidable - and kind of scary for young Ursula. She taught Charlie all that she knew from a young age. Maddie asks why she was scary, though.
Ursula explains that neither of their families were very happy about the wedding, but they married anyway. Ursula takes off to her knitting club and invites Deb to come along, but knitting isn't Deb's style, and she leaves to go find a cute mailman she saw earlier.
Roddy visits. He dreamily wonders what it would be like to get lost in the maze with Maddie, but she's not really listening. She's thinking back to Charlie's phone call. She asks Roddy if she can tell him a secret...
Roddy learns about Charlie's notebook, and his statement that it would lead to everything Maddie wants - but it's not helping Ursula at all! Roddy says they may need patience. He takes a look at the book too, and seems to understand something - but is reluctant to talk.
Roddy notices that the sketch looks like some kind of a clock! Maddie realizes he's right! In order to get the next clue they have to build a sundial using Charlie's notes!