chains up

Chains up means to secure something or someone with chains, typically to restrict movement or prevent escape.

You might chain up a bicycle to a rack, chain up a dog in the yard, or chain up a gate to keep it closed.

The phrase can also describe putting tire chains on a vehicle for winter driving: We had to chain up before crossing the pass.

In darker contexts, it suggests imprisonment or restraint: The captives were chained up in the basement.