It should have been a victorious moment–

he had just opened his very own medicine shop.

But he bought his supplies from his former employer,

and the resentful man sold him rotten herbs.

As Xu Xian wondered what to do with this useless inventory,

patients flooded into his shop.

A plague had stricken the city,

and he had nothing to treat them.

Just as he was starting to panic,

his wife, Bai Su Zhen, produced a recipe to use the rotten herbs as medicine.

Her remedy cured all the plague-afflicted citizens immediately.

Xu Xian's former boss even had to buy back some of the rotten herbs

to treat his own family.

Shortly after, a monk named Fa Hai approached Xu Xian,

warning him that there was a demon in his house.

The demon, he said, was Bai Su Zhen.

Xu Xian laughed.

His kindhearted, resourceful wife was not a demon.

Fa Hai insisted.

He told Xu Xian to serve his wife realgar wine on the 5th day of the 5th month,

when demons' powers are weakest.

If she wasn't a demon, he explained, it wouldn't hurt her.

Xu Xian dismissed the monk politely,

with no intention of serving Bai Su Zhen the wine.

But as the day approached, he decided to try it.

As soon as the wine touched Bai Su Zhen's lips,

she ran to the bedroom, claiming she wasn't feeling well.

Xu Xian prepared some medicine and went to check on her.

But instead of his wife,

he found a giant white serpent with a bloody forked tongue in the bed.

He collapsed, killed by the shock.

When Bai Su Zhen opened her eyes,

she realized immediately what must have happened.

The truth was that Bai Su Zhen was an immortal snake

with formidable magical powers.

She had used her powers to take a human form

and improve her and her husband's fortunes.

Her magic couldn't revive Xu Xian,

but she had one more idea to save him:

an herb that could grant longevity and even bring the dead back to life,

guarded by the Old Man of the South Pole

in the forbidden peaks of the Kun Lun Mountains.

She rode to the mountains on a cloud,

then continued on foot passed gateways and arches

until she reached one marked “beyond mortals”

hanging over a silver bridge.

On the other side,

two of the Old Man's disciples guarded the herb.

Bai Su Zhen disguised herself as a monk

and told them she'd come to invite the Old Man to a gathering of the gods.

While they relayed her message,

she plucked some leaves from the herb and ran.

The servants realized they had been tricked and chased her.

Bai Su Zhen coughed up a magic ball and threw it at one.

As the other closed in on her,

she put the herb under her tongue for safekeeping,

but its magic forced both of them into their true forms.

As the crane's long beak clamped around her,

the Old Man appeared.

Why, he asked, would she risk her life to steal his herb

when she was already immortal?

Bai Su Zhen explained her love for Xu Xian.

Even if he didn't want to be with her now that he knew she was a demon,

she was determined to bring him back to life.

The two had a karmic connection dating back more than a thousand years.

When Bai Su Zhen was a small snake,

a beggar was about to kill her,

but a kind passerby rescued her.

Her rescuer was Xu Xian in a past life.

Touched by her willingness to risk her life for him,

the Old Man permitted her to leave the mountain with the immortal herb.

Bai Su Zhen returned home to revive Xu Xian.

When he opened his eyes,

the terrified look frozen on his face became a smile.

Demon or not,

he was still happy to see his wife.