Seeing Is Believing Mission Walkthrough in Lego Batman: Legacy of the Dark Knight

Seeing Is Believing is one of the optional detective threads tucked inside Ace Chemicals, the same location featured in Lego Batman: Legacy of the Dark Knight's main campaign. The mission leans on environmental clues left behind by Jervis Tetch, ending with Batman crashing a tea party staged by a room full of teddy bears.

What the mission actually is

Seeing Is Believing is an environmental side objective tied to the Ace Chemicals story beat. It is not a standalone open-world contract. Instead, it lives inside the level itself, gated behind two concealed rooms that the main path lets you bypass entirely.

The trail belongs to the Mad Hatter, even though Jervis Tetch never appears as a boss in the base campaign. The chemical plant is being used as his hideout, and the puzzle rewards you for noticing it.

Requirements before you start

The mission becomes reachable once you are inside Ace Chemicals during the main story. You need Batman's standard kit, which includes the grapple, batarang, and glide ability. No special suit unlock is required, and the optional puzzle does not demand a second playable character.

Finding the first hidden room

The opening clue is the puzzle-locked chamber. It is entirely optional, so the standard objective marker will not steer you toward it. You have to wander off-path inside Ace Chemicals and look for an interactive panel that breaks the room's normal flow.

Step 1: Pause the story objective and sweep the interior of Ace Chemicals for a sealed side area. The door is gated behind a small environmental puzzle rather than a key item.

Step 2: Solve the puzzle to unlock the room. Inside, you will find a red table set with a teapot and two teacups, which is the first concrete sign that Jervis Tetch has been squatting in the facility.

Step 3: Interact with the table to register the clue. This is the verification step. The game treats the tea set as evidence that ties the chemical plant to the Mad Hatter.

Finding the second hidden room

The second area is the payoff. It is a larger concealed room filled with teddy bears arranged around a long tea table, mimicking the unbirthday party from Alice in Wonderland.

Step 1: Continue exploring Ace Chemicals after clearing the first room. The second hideout is in a separate part of the level and is not linked directly to the first chamber.

Step 2: Enter the room and approach the seated teddy bears. Batman can join the tea party as an interactive event, which is what completes the optional sequence.

Step 3: Trigger the sit-down animation to finish the moment. Once Batman takes part, the Mad Hatter connection is locked in, and an unlockable Batcave prop referencing Tetch becomes available for display.

How to confirm it worked

You will know the trail is closed when Batman participates in the teddy bear tea party and the related Batcave prop unlocks. The Batcomputer's customization options also reflect the new collectible, which you can later place inside the Batcave alongside other vehicles, trophies, and themed items.

Common reasons it does not trigger

If the sequence is not registering, the cause is almost always that the optional puzzle was skipped or that the second room was never entered. The story path through Ace Chemicals does not pass through either chamber, so brute-forcing the main objective will lock you out until you replay the mission.

If any of the above apply, head back to the mission select screen and replay the Ace Chemicals chapter. The hidden rooms reset along with the level, and the Mad Hatter trail becomes available again from the start.