Here's one approach: open an Arcane Gate (10th level wizard utility, minor action to create and sustain).
Someone steps through the Gate (move), picks up the PC (some combinatin of minor and/or standard), then spends an Action Point to step back through the Gate.
Other PCs defend the gate for the rest of the round against attempts by NPCs to come through it. Then the gate closes and the PCs move out.
The gate requires line of sight to the NPC, but that can be done by eg opening a door.
************************************
Here's another option: A warlock sneakes into the room, gets close to the NPC, and then makes an Arcana check to improvise Warlock's Leap (6 sq non-line-of-sight-required teleport, personal only) to act on another target instead, sending the NPC to some useful PC-controlled hidey-hold within 30' (eg on the other side of a wall, beneath the floor, etc). Then sneaks out again.
**********************************
Here's another option, though it depends on an ability that is higher than 10th level: use True Portal to open a portal to where the NPC is. The duration is 1, 3 or 5 rounds depending on success with an Arcana check.
By my reading, a portal ritual defaults to one-way, so you would need to make an Arcana check to modify the ritual to have it be two-way. Having successfully created a two-way portal you step through, rescue the NPC, and step back, letting the portal close behind you.
I just saw your post. As I said, I'm not sure whether a 4e portal ritual is 2-way by default or needs an Arcana check to vary it. But anyway I think we're pretty much on the same page.
Arcane Gate has been hugely important in our 4e game - probably the most impactful of all the PCs' utility powers. The character who uses it started out as a wizard and then
rebuilt as an invoker at 15th level following a life-change event, but spent the feat to keep Arcane Gate because it's just that good.