I am currently doing my second playthrough of the game and have reached The Cure for Madness quest in the Dark Brotherhood chain. Astrid tells me to follow Cicero and offers up Shadowmere, the quest objective properly switches to 'behold Shadowmere'. So, I go outside and watch the black lake bubble for a little while, the audio working fine. The sound of galloping hooves, Shadowmere neighing, a lightning crash. You know, the usual. Only the horse never shows up. The quest objective updates to where I need to find Arnbjorn, though, effectively skipping Shadowmere completely. I've reloaded and tried about 5 or 6 times, I've turned off the console and tried. Every time, same thing happens: bubbling lake, audio, no horse. I have no idea what could be causing it and it isn't particularly gamebreaking (though I do really want that horse). The only things that have changed from my first playthrough (besides the obvious like build and equipment) is the quest order I've done. On my new character, the Dark Brotherhood is the first quest chain I am actually doing (I have started the Thieves Guild and the Stormcloak chains. Haven't done any of the actual quests past the ones necessary for entry into the faction). I also have done all of the Dark Brotherhood contracts by now, whereas I was still on the set of two (the wizard and the housecarl) in my first playthrough. I was just wondering if they had been notified of this glitch or if anyone else had a similar problem. Thanks.

Edit: Just clarifying that I searched through the forum and on other places and found no mention of this bug on any other site out of the ones I visited.

Same here. I get the audio-- but no Shadowmere. I can't find any info on this anywhere. It's really frustrating. I tried fast traveling and reloading, but still nothing.

Well I had a bug too, not this one, but somehow he has been replaced by a normal horse I walk into the Sleeping Giant Inn, come out and see a regular horse where he should be

I had the same problem. After searching on the net I came across the cheat code of salvation: player.placeatme 0009CCD7
Shadowmere with spawn next to you in full health and ready to go.

Shadowmere's disappearance must be a bug so if you are a PC user just use this cheat until Bethesta releases a patch to fix the bugs, as i hope they will. =P

If u use XBox or PS3 the best solution I've found is to retrace your steps and maybe you'll find her where you left her. GL

I am having the same issue on the PS3. I did the quest on my first char and it worked fine but I ended up remaking my char due to poor perk choices. When I did the quest on the new char Shadowmere never spawned during "Behold Shadowmere". I have tried several different things to get him to spawn (killing my current horse, fast travel, having my spectal assasin out, changing to a vampire, changing to a werewolf, waiting till early or late evening, waiting till early or late morning, resetting the game, resetting the console, doing more main storyline and comming back) but nothing seems to help. This current problem and the fact that daggers are broken and not affected by one handed enchants is starting to ruin my Skyrim experience.