Excerpt from I Married You for Happiness by Lily Tuck, plus links to reviews, author biography & more

For their honeymoon, they go to Mexico, to look at butterflies. Butterflies? Why? Nina tries to object.

Monarch butterflies. Millions of them. It's still early in the migratory season, but I've always wanted to see them. And afterward we can go to the beach and relax, Philip promises.

The car, an old Renault, is rented, and the roads are narrow and wind steeply around the Sierra Chincua hills as they drive from Mexico City to Angangueo. There are few cars on the road; the buses and trucks honk their horns incessantly and do not signal to pass. There are no signs for the town.

Donde? Donde Angangueo? Philip repeatedly shouts out of the car window. Standing by the side of the road, the children stare at him in mute disbelief. They hold up iguanas for sale. The iguanas are tied up with string and are said to be good to eat.

Supposedly they taste like chicken, Philip says.

How do you know? Nina asks.

Instead of replying, Philip reaches for her leg.

Keep your hands on the wheel, Nina says, pushing his hand away.

In Angangueo, they stay in a small hotel off the Plaza de la Constitución; there are no other tourists and everyone stares at them. Before they have dinner, they go and visit the church. On an impulse, Nina lights a candle.

For whom? Philip asks.

Nina shrugs. I don't know. For us.

Good idea, Philip says and squeezes her shoulder. The next morning, when they get out of bed, their bodies are covered with red bites. Fleas.

Following the hired guide, they hike for over an hour along a winding, narrow mountain path, always going up. They walk single file, Philip ahead of her. Tall and thin, Philip walks with a slight limp - he fell out of a tree and broke his leg as a child and the tibia did not set properly - which gives him a certain vulnerability and adds to his appeal. Occasionally, Nina has accused him of exaggerating the limp to elicit sympathy. But most of the time, his limp is hardly noticeable except when he is tired or when they argue.

The day is a bit overcast and cool - also they are high up. Eight or nine thousand feet, Philip estimates. Hemmed in by the tall fir trees, there is no view. It is humid and hard to breathe.

How much farther? She wants to ask but does not when all of a sudden the guide stops and points. At first, Nina cannot see what he is pointing at. A carpet of orange on the forest floor. Leaves. No. Butterflies. Thousands and thousands of them. When she looks up, she sees more butterflies hanging in large clusters like hives from tree branches. A few butterflies fly listlessly from one tree to another but mostly the butterflies are still.

They look dead, she says.

They're hibernating, Philip answers.

On the way back to town, Philip tries to explain. There are two theories about how those monarch butterflies always return to the same place each year - amazing when you think that most of them have never been here before. One theory says that there is a small amount of magnetite in their bodies, which acts as a sort of compass and leads them back to these hills full of magnetic iron, and the second theory says that the butterflies use an internal compass -

Nina has stopped listening. Look. She points to some brilliant red plants growing under the fir trees.

Limóncillos, the guide says and makes as if to drink from something in his hand.

Sí, Nina answers. By then she is thirsty.

From Angangueo, they drive to Puerto Vallarta, where they are going to spend the last few days of their honeymoon. In the car, Nina shuts her eyes and tries to sleep when all of a sudden Philip brakes and she is thrown against the dashboard. They have hit something.

Oh, my God. A child! Nina cries.

A pig has run across the road before Philip can stop. His back broken, the pig lies in the middle of the road, squealing. Each time he squeals, dark blood fills his mouth. Within minutes and seemingly from out of nowhere, men, women, and children have gathered by the side of the road and are watching. Philip and Nina get out of the car and stand together. It is very hot and bright. Putting her hand to her head to shade her eyes, she says, Philip, do something. The pig sounds just like a baby.

Excerpted from I Married You for Happiness by Lily Tuck. Copyright © 2011 by Lily Tuck. Excerpted by permission of Atlantic Monthly Press. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.