Here's what not to do: Run around the garden with the whining desperation of Clytemnestra moaning their names. Then, when you've calmed down, crouch in the bushes and make guinea-pig noises, like your husband is doing two bushes over. Don't bother getting out the flashlight and flicking it around under the clubhouse, beneath which you hope they've tucked themselves: this probably makes them feel like the character in a detective drama with the light trained in his eyes and the question, "Where were you on the night of July 4th?" ringing in his ears.
Don't go to bed desperate assuming they've been consumed by foxes, dogs, cats, or squirrels. Assume they can deal with the moles who have taken over the garden, including parts of their acreage in their little outdoor cage, by themselves.
How did they get out of their cage? Or were they dragged? There's a cat who sniffs around occasionally--I throw empty shampoo bottles at him from the upstairs bathroom and he glares, but runs.
Oh, the cage isn't on level ground. There's one corner with just enough space for an enterprising young guinea pig to squeeze out, and that's what she did, taking the older, more sedate one, with her. And now where are they?
Go to bed. Have bad dreams.
Wake at 1:00. It is raining. Go down to the garden again and look under the slide, where you've looked ten other times.
At 5:00, wake and Google escaped guinea pigs.
Since you don't have a hav-a-hart cage, take all their little houses, the ones from the indoor cage, the ones from the outdoor cage, the ones sitting on the woodpile. Place them around the bushes under which you hope the girls crawled. Place carrots or alfalfa hay at the entrances or inside. Look around. Go back to bed.
At 10:00 a.m., wake from stupified nightmares to the sound of driving rain and thunder. Go downstairs with umbrella, decide to check the houses. Nothing in the first, the one you put under the slide, the place they loved to hide the other time they got away. But that time you were right there.
Check box two. Astonished to see two perfectly dry guinea pigs huddled together, scream. When you scream, the fast one shoots out into the bushes. She's now drenched. Put house back down on other, slower, startled piggie and talk to them: "Oh, thank goodness you're here. Oh, Ginny. Oh, Lily, please come back, Lily, please do come back. Lily gives you a look. Sorry, Lily, my bad. The rain, the cage, whatever you say. Come back, little Lily. So she races into the house. This time, you don't scream. You put down your umbrella, you lift the box and scoop them both up, you bring them inside and wrap them in a dry towel. They have declared their independence and now they are back home, eating carrots and cuddling.