Knows Harry can track him

"And while we're cooperating with the authorities, what happens to Abby, Helen, and Priscilla?" She stared at me. "For that matter, what happens to Mouse?"
That was a thought I'd been trying to avoid. If Mouse was alive and capable, there was no way he'd let any of the women be harmed. If someone had killed Anna when Mouse was near, it could have happened only over his dead body.
But there was no sign of him.
That could mean a lot of things. At worst it meant that he had been utterly disintegrated by whatever had come for the women. Not only was that assumption depressing as hell, it also didn't get me anywhere. A bad guy who could simply disintegrate anything that got in the way sure wouldn't be pussyfooting around the way these White Court yahoos had been.
Mouse wasn't here. There was no mess, no sign of a struggle, and believe you me, that dog can put up a struggle, as the vets found out when they misfiled his paperwork. They tried to neuter him instead of vaccinating him and getting his shoulder X-rayed where he'd bounced off of a moving minivan. I was lucky they were willing to let me pay the property damage and leave it at that.
It had to mean something else. Maybe my dog had left with the others, and Anna had remained behind, or gone back for something she forgot.
Or maybe Mouse had played on everyone's expectation that he was just a dog. He'd shown me that he was capable of that kind of subterfuge before, and it had been one of the first things that tipped me off to his distinctly superior-to-canine intellect. What if Mouse had played along and stayed close to the others?
Why would he do that, though?
Because Mouse knew I could find him. Unless the bad guys carried him off to the Nevernever itself, or put him behind a set of wards specifically designed to block such magic, my tracking spell could find him anywhere.
That was the path to take, even if Mouse didn't know anything was wrong. He would have stayed with any members of the Ordo that he could, and I had taken to planning ahead a little more than I used to do. I could use my shield bracelet to target the single small shield charm I'd hung from his collar for just such an emergency. Me and Foghorn Leghorn.

White Night Chapter 25, Page 251


My tracking spell led us to an apartment building.
"This is Abby's building," Elaine said as I pulled over. The only close place to park was in front of a hydrant. I doubted any industrious civil servants would be handing out tickets this late, but even if they were, it would be cheap compared to what a long walk in the dark could cost me.
"Which apartment?" I asked.
"Ninth floor," Elaine replied. She shut the door of the Beetle a little harder than she had to.
"It occurs to me," I said, "that if I was a bad guy and wanted to off a couple of intrepid hard-boiled wizards, I might be hanging around watching someplace like this."
"It occurs to me," Elaine said, her voice crisp, "that he would be exceptionally foolish to make the attempt."
We walked together, quickly. Elaine was tall enough to keep up with me without taking the occasional skipping step. She'd slipped half a dozen coppery bracelets over each wrist, all of them slender, all of them hanging more heavily than they should have. Faint glints of golden energy played among them, and looked like little more than the glitter of light on metal - except that you could see them better when the bracelets were in deep shadows.
By silent agreement, we skipped the elevators. I had my shield bracelet ready to go, and my staff was quivering with leashed energy that made it wave and wobble incongruously to its weight and motion as I moved. That much readied magic could have unfortunate consequences on electrical equipment, like elevator control panels.
The doors to the stairs opened only from the other side, but I conjured a quick spell to shove against the pressure bar on the far side using my staff, and it swung open. We slipped into the stairway. Anyone waiting for us above would be watching the elevator first. Anyone chasing after us would have a hard time with the locked doors, and would make noise on the open concrete stairs.
I checked my gun with my left hand, safe in the pocket of my duster. Magic is groovy, but when it comes to dealing out death, regular mortal know-how can be just as impressive.
Nine floors up was enough to make me breathe hard, though not as hard as I once would have. A faint ghost of a headache came along with the elevated heart rate. Hell's bells, I must have been hurt a lot worse than I thought, back at the harbor. Elaine looked a little strained, herself. If she'd really smoothed away that much of an injury, she had more skill than she'd told me she did. That kind of healing isn't a matter of trivial effort, either. She might be more fragile than she appeared.
I opened the fire door on Abby's floor, and let Elaine take the lead. She went down the center of the hallway in total silence, her hands slightly outstretched, and I got the sense that she was somehow perfectly aware of everything around her - more so than human senses would account for. The bracelets on her wrists glittered more brightly. Superior awareness as a defense, then, instead of my own, more direct approach of meeting power with power and stopping things cold. Just her style.
But neither hyperawareness nor irresistible force was called for. Elaine reached a door and raised a hand to knock. Just before it fell, the door opened, and a strained-looking Abby gave us a quick nod. "Good, a little early, that's good; come in, yes, come in."
I started forward, but Elaine held up one hand to halt me, her eyes distracted. "Let me check. Another woman inside. Two dogs." She glanced at me, and lowered her hand. "One of them is your dog."
"Mouse?" I called.
The floor shook a little, and the big, dark grey dog nudged rather delicately past Abby and came to greet me, shoving his head into my stomach until I went down on one knee and got a sloppy kiss or two on the face.

White Night, Page 257-258