Control Resonant: How to Cross the Underpass Pipes With the Probe Relay

The Underpass saves its most awkward bit of platforming for last. Once Recursions and Iterations asks you to follow the relays to Grist, the final stretch of the mission hands you a probe relay and strips out most of your traversal kit, leaving a network of rusted pipes strung over dark water as the only way forward in Control Resonant. It is not a puzzle so much as a balance test with a very specific line to follow.

Quick answer: Pick up the probe relay beside Grist, walk onto the rusty pipe along the chamber wall, climb the concrete ledge, jump to the higher pipe, then follow it through the tunnel into the cavern.

Where the pipe crossing starts in the Underpass

The crossing sits at the tail end of the mission, after the chasm section at the cable car. Getting there means dropping through the flooded lower levels of the Underpass, climbing the red-lit concrete ledges, and jumping between pillars and platforms until the relay trail picks up again.

Crossing Toward the Cable Car — The platform jumps leading toward the cable car, before the relay trail resumes. Shown at 00:33 in Trophy Guides’s video. Image: Remedy Entertainment

Follow the trail to the end and you reach a dim chamber with Grist lying on the floor. The last probe relay is on the ground right beside him, and the objective updates to Place the Final Probe Relay as soon as you get close.

Finding Grist and Relay — Grist's body and the final probe relay, where the pipe route begins. Shown at 00:02 in Trophy Tom’s video. Image: Remedy Entertainment

What the relay does to your movement

The relay counts as a carried object, and the game locks out your usual mobility while it is in your hands. That is the whole reason the pipes exist here — you cannot simply shortcut the gap. Walking and jumping still work fine, which is all the route needs.

On-screen prompt	What it means
L1	Lift the relay with telekinesis
! Not While Carrying	That ability is blocked until you put the relay down
Drop Object	Set the relay on the ground at any point
Activate	Switch the relay on once it is in the drop spot

If a jump feels too tight, drop the relay, reposition yourself, then pick it back up. Nothing resets, and the relay stays where you leave it.

How to cross the pipes carrying the relay

Pick up the probe relay from the floor next to Grist using telekinesis. Hold it and turn back toward the chamber wall, where a large rusty pipe runs along the side of the room.

Step up onto that rusty pipe and walk along it. The pipe is wide enough to stand on comfortably, so keep your movement steady rather than sprinting and correcting.

Mounting the Pipe — Mounting the rusty pipe with the relay in hand. Shown at 00:20 in Trophy Tom’s video. Image: Remedy Entertainment

Follow the pipe until it meets a set of concrete blocks, then climb up onto that ledge. From the top, jump across to the higher pipe segment that curves overhead along the corridor.

Navigating Elevated Pipes — The concrete ledge and the curved piping you step across next. Shown at 00:24 in Trophy Tom’s video. Image: Remedy Entertainment

Walk the elevated pipe through the narrow passage ahead. This is the tightest part of the route, so take it slowly and keep the camera pointed down the length of the pipe instead of out over the drop.

Stay on the pipe through the tunnel until it opens out. The moment the ceiling lifts and the space widens, the crossing is done and you are standing in the large cavern.

Reaching the cavern on the far side

The cavern is easy to identify. It is open, far brighter than the tunnel you just left, and there is a raised mound in the middle with a single small tree on it. That tree is the destination for the relay, and the yellow quest marker sits directly over it.

Walk the relay over to the mound, drop it into the marked spot near the tree, and activate it. That closes out the final objective of Recursions and Iterations, and the mission pays out the Prime Candidate Restraint outfit along with a Living Shard.