The cache is NOT at the posted coordinates! This used to be a nice place to park though, but the parking has moved up the street (use parking waypoint; lot can fill quickly - alternate parking also in waypoints). It is not necessary to find this bonus cache the same day you do the Adventure Lab, although you will walk right by it on the way out... Container is adequate size for small TBs and geocoins and some swag. NO night caching - your safety is your responsibility. Search for this Adventure and bonus cache at your own risk. Know your limits, have a plan and let someone know where you're going. Congratulations to Soccertoa on the FTF!
DEC 2022 EDIT: Access to the tunnel at Stage 2 of the Adv Lab is currently closed due to construction. You can get close and still follow the instructions, just don't need to go all the way down to the stream. Answer for Stage 2 is in the description both in the AL and in the waypoints of this cache.
Difficulty and terrain reflect the Adventure Lab. These are trails, folks - nice rustic ones with roots and rocks. Lab takes you down by the river and involves a STEEP section near the farthest point. This bonus cache does not require anything death-defying though. Most of the hard work will be done by the time you get to this final location. Scroll down for important information about the Adventure Lab
Discover the data needed to determine the coordinates for this mystery cache by completing the Who Stole Sammy Squirrel's Nuts? Adventure Lab. You will need a smartphone with data service and the Adventure Lab app installed. You can install the app by going to https://labs.geocaching.com. Waypoints for each stage of the Adventure Lab are included here for reference.
Launch the adventure by opening the Adventure Lab app and browsing to "Who Stole Sammy Squirrel's Nuts? A Mystery Trek", or by using this direct link on your smartphone, which should open the adventure in the app.
The Mountain And The Squirrel
By Ralph Waldo Emerson
The mountain and the squirrel
Had a quarrel,
And the former called the latter "Little prig."
Bun replied,
"You are doubtless very big;
But all sorts of things and weather
Must be taken in together
To make up a year
And a sphere.
And I think it no disgrace
To occupy my place.
If I'm not so large as you,
You are not so small as I,
And not half so spry:
I'll not deny you make
A very pretty squirrel track.
Talents differ; all is well and wisely put;
If I cannot carry forests on my back,
Neither can you crack a nut."
Source: www.familyfriendpoems.com/poem/the-mountain-and-the-squirrel-by-ralph-waldo-emerson
Once you've completed the adventure, you should have 2 numerical clues (a three-digit and a 4-digit number) and a hint from Officer Tortoise. Use those clues to complete the final coordinates. If you need to retrieve the codes, you can reopen the adventure in the app and view the journal entries.
The suspect confesses that he hid Sammy's stolen stash in a location near the scene of the crime. Under interrogation, the thief says that to find the stash, adjust the posted coordinates as follows:
ADD the LAST TWO digits of the 4-digit clue to the North coords
ADD the 3-digit clue to the West coords
Do the math and take a look, but ... what was that last thing Officer Tortoise had to say?
Checksum for the 5 digits you need is 27.
The following pertains to the Adventure Lab, not necessarily to the Bonus Cache! The Lab Builder doesn't allow for a lot of text information and I believe the nature of this trail warrants being a little more prepared! If you know the area, know the trails and want to take on the adventure - go for it! There's nothing here you can't get out of the Adventure Lab app. However, if you want to know a little more about where you're going and the trails you'll be using, read on... I personally don't think Labs should be hard, rather they should be fun even if they include a little challenge!
The video at the first stage of the lab gives a view of driving to the parking area and hiking past the first stage and even to one of the latter stages: Here is the link: https://youtu.be/1XZnC5yNeO4 Worth a watch before heading out. He does not go down to the really steep section at the farthest point of this adventure.
Park at the PARKING waypoint or at alternate parking. Hilltop Road is narrow and curvy, and parking along the portion of the road through park property is not allowed. From the parking area, head left on the crushed stone/gravel path. You'll follow that gravel path (red blazes), continuing straight as it becomes the yellow-blazed Buzzards Rock Trail when the Sawmill Branch Trail turns off to the left (this intersection is shown as the Trailhead in the waypoints). If you use the alternate parking, you'll follow a trail that loops down a bit and back up, picking up the red blazed gravel trail slightly before you get to this BuzzardsRock trailhead (will now be a left for you!). It's about a half mile or so hike from alternate parking to the posted trailhead waypoint, but don't let that discourage you - it's not much further than the hike in from the posted parking area.
Other than a few rocks and roots, the trail is really pleasant and relatively flat. However, after passing stage one of the Lab and shortly before Buzzards Rock, the trail starts to descend rapidly and it's quite steep in the last few hundred feet. Like, rock scramble steep. Not that you'd need a rope, but use caution, particularly in wet or leafy conditions. At the top of the very steep section, go right around the largest boulder - that will give you more stone "steps" to descend on rather than washed out dirt. Once you descend, you'll see the train tracks through a small trail to the right, and some "stairs" going down to a stream. Follow the stream (Pig Run) through the tunnel to where the Patapsco River is visible for stage 2.
IF you wish, you can bypass the steepest section of the yellow trail by taking the turnoff the teacher references in the video (Reference point in the waypoints). You'll pass Face Rock on the way down to another trail. There is still a steep section, but not nearly as much as continuing on the yellow trail. The cut off trail to face rock is new and not well marked but there currently are still pink flags along the way. This alternate circles back around - when you come down the rock slab-by section it intersects with the Sawmill Branch Trail again. Hang a right here and continue down to the top of the "stairs" referenced above. Going this route passes Stages 3 & 4 but you can't do them yet - don't worry, you'll come out the same way!
NOTE: cell service can be spotty at the lowest part of the valley. The "geofences" for stage 2 have been extended some to account for this - try coming back through the tunnel and up the trail towards stage 3 a bit. You can always try the mantra "Can you hear me now?" 
After stage 2, go back through the tunnel and up the stairs, heading right on the Sawmil Branch Trail (You DON'T go back up the super steep section!). If you came down the alternate way, you know where the trail turnoff is to go up to Face Rock. The trail turnoff is Stage 3 and Face Rock is stage 4 (if you look closely you can usually see Ahnahu staring down at you as you walk the Sawmill Branch Trail!). Stage 5 is at Buzzards Rock and there you'll name your suspect before heading back out, patting yourself on the back for collaring Sammy Squirrel's stash swiper! If this is one of your first Adventure Labs, note that the app tends to jump to a "Congrats" completion page after the final answer, skipping the final journal page (which incidently holds the key to the bonus cache!). You can go back and reference all of your journal pages inside the app.
The bonus cache is located just off the yellow trail and along the route back to your geo-mobile. You'll have to go into the woods just a bit (like 75' or so) but there usually isn't much undergrowth. Due to the nature of the valley, allow your GPS signal to settle! Please be sure the container is well-hidden and not visible from the trail. There is a solution checker on this page to be sure you've got the right location for the container.
Adventure Lab and bonus cache are MD DNR/Patapsco Valley State Park approved.
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If you read all the way down to here, perhaps you'll go a little farther with me for something a little interesting?
This Adventure Lab contained two instances referencing pareidolia. Pareidolia is a psychological phenomenon that causes people to see patterns in a random stimulus. This often leads to people assigning facial characteristics to inanimate objects. In darker times, the ability to "see" these characteristics was thought to be a sign of psychosis, but since we've evolved from the days of "Burn it - it's a witch!" now some think that everyone can do it. If anything, it may be more prevalent in detail-oriented people. Tha Adventure lab contains a "face" rock and the outlines of Officers Eagle & Tortoise! There are several trees I've noticed in local walks in the Catonsville area that stand out as being "more than a tree." Most notably the Cyclops and the Hugging Trees found on the #8 Trolley Trail. Hmmm....sounds like plans for a mystery cache in the future on this similar topic... who knows, maybe I'll give a clue in this container if it comes out....