This mission starts in the Clock Tower Courtyard, so open your map and navigate to the South Wing. Then, find the closest Floo Flame to the quest marker, and magic your way there! Go to the well, and then find the statue indicated by the objective marker. In its beak, you’ll find the note from Scrope — collect it by pressing /.
Search for the next note
Next, follow the path of yellow dots on the minimap — they’ll lead you over the iconic bridge that leads south-southwest, away from the castle. Once you reach the other side of the bridge, look at the second rock on the left, where you’ll see the next note perched (1). You’d think you could cast a spell to grab it, but no, you’ve got to instead move the nearby crate (2). Target it and cast Levioso, then Accio, to bring it next to the note (3). You can then climb up onto the crate with / and grab the note with /.
Search the pumpkin patch for another note
Again, follow the path on the minimap — it’ll lead you on a path south and then east down the hill (you can take a shortcut off-road if you’re impatient(1)) to the pumpkin patch. Once there, stand near the scarecrow and cast Revelio with — this will reveal a note in a pumpkin near the house (2). Hold , aim at the pumpkin with the note, and tap to Basic Cast the pumpkin to bits. You can then pick up the note.
Meet Scrope at the water’s edge
Now you’ll need to again follow the path on your minimap, or simply head straight to the water’s edge by going north-northeast around the house. Make sure you Basic Cast and collect the moonstone on the left side of the path near the water (1) on your way there. Stand on the spot indicated by the objective marker (2) and a conversation will begin in which you’ll meet Scrope.
Investigate the Grotto
Your next objective is to the north, so start following the shoreline towards the objective marker (1). You’ll have to cross the water at one point to continue, but you’re slow in water, so try to only enter it where necessary. Be careful — shortly after crossing the first bit of water, you’ll be attacked by Stoneback Dugbogs. They can be pretty tough, so here are some tips:
Be ready to dodge, since a lot of their attacks cannot be blocked with Protego.
You can cast Levioso on them, but only while their tongue is explosed.
You’re also faster than the dugbogs, so worst come to worst, you can just run past them, Dark Souls style. Swim to the nearby island, sprint across it, then get back in the water and head through the narrow cleft in the cliffs ahead (2). You’ll enter a cave with dry land on the far side. Make your way to the pedestal (3) and press / to place some toast on it — this will start a rather interesting cutscene.
When it ends, head through the newly opened hole in the wall to enter a room full of oddities. On the right behind the folding screen is a chest (1), open it with / to gain access to the side quest “Ghost of Our Love”. Then turn around and go over to the table (2), where you can collect Apollonia Black’s Journal with /, starting a cutscene. Feel free to ask Richard Jackdaw some questions — I know I was curious about the toast — and then end the conversation.
Return to Scrope
Now you’ve got to go back the way you came, in order to meet Scrope. If you ran away from the Dugbogs, they’ll have followed you fairly close to the grotto, so be ready to run past them again — they don’t seem able to attack you while in the water (same as you). If you’re feeling braver, you can also choose to fight them this time! Scrope is right where you found him — don’t forget you can tap to have your compass guide you if you aren’t sure how to get back to Scrope.
That concludes this quest — the next Main Story quest is Jackdaw’s Rest, but before you do that, you’ll need to unlock Expelliarmus by completing Professor Hecat’s Assignment 2, so make sure you’ve done the requisite tasks.