Thor, Odin, Sif, and Heimdall remained silent for a long moment after what Heimdall had said. The tension in the room was so thick right now. They knew what needed to be done but none of them were eager to say it.
The chamber was so quiet that Thor could hear his own breath. They could storm Valeria's stronghold and rescue Erik and Mia but that would only make things worse. Valeria would become even more dangerous, harder to catch, and they'd lose their inside advantage. The cost was too high.
And they don't believee that Valeria will be that easy to catch even though they have the element of surprise. Someone else is helping her planning and doing all of this. Someone they don't know yet, so they can not act rashly.
Finally, Odin broke the silence. He said. "We proceed according to the plan."