When Mr. Ages arrived at his lab he was very tired. Martin met him at the door.
The fatigue of his years showed so Martin helped Mr. Ages reach his desk.

Martin had become a faithful student to Mr. Ages, as Mrs. Brisby had requested.
Why? because he would be the one in charge of the household if his mother or
his Auntie were to suffer some unfortunate mishap.

Also, he loved to 'play' with Mr. Ages' equipment (though, of course, under his
strict supervision). Cynthia was with Martin at the lab because his mother had
asked him to take her with him (she really wanted Cynthia out of the house so
she could prepare a special surprise for her).

But now Martin was coming to realize that playing with Mr. Ages' instruments
wasn't so much fun. Not now that he was the one that was having to watch over
Cynthia - and his little sister was not exactly being a little angel.

Cynthia was having a lot of fun grabbing one thing after another and pestering
Martin with endless questions. But fortunately he had found a way to keep her
quiet, reading to her from some of Mr. Ages' notes about
the behavior of animals; how they lived, what they ate and how they protected
themselves from predators. However, when they came to the part about
reproduction, neither Cynthia or Martin understood what was written.
Furthermore, Mr. Ages had not illustrated many of his notes with drawings, and
when he did it was for himself to more easily visualize what his ideas were, so
his drawings always just looked like a random mix of thin lines, irregular and
devoid of any geometric sense. Cynthia, however, could make some sense of the
scribblings. Here and there she would recognize the shape of some animals,
(although not the of the ones that Ages had wanted to depict), and she had a
lot of fun trying to figure out, with her limitless child's imagination, all
the animals she could recognize.

But what was about to happen was far from a game. On the contrary, it was a
question of life or death; there was no time to lose.

"Hurry Martin!," Mr.Ages snapped. "Put all my chemicals in my
bag and grab as many of the medicines you can, of as many colors as you can,
for goodness' sake boy, get goin'!!" Martin was still quite stunned. He
had never seen Mr. Ages so terribly distressed before. Martin was so confused
that he didn't even know where to begin. Mr. Ages noticed Martin's
bewilderment.

"Dammit Martin! Hurry UP!!!!!". Martin roused from his mental lapse
and began to snatch up any and everything he could.

Cynthia interrupted her little game, seeing that Mr. Ages was not acting like
himself. "Mr. Ages, can I draw on your paper?" Cynthia, in her own
childish world, didn't quite realize what was going on.

Mr. Ages, finding that Cynthia was there, pestering her brother, tried to calm
himself as much as possible, breathing very deeply so he would not lose his
temper but most of all, to not lose his temper over Cynthia.
"Please let your brother do what I told him to, don't be a nuisance."
Cynthia gave Mr. Ages a sweet and innocent look, obeying him while Martin
dashed from one end of the room to the other, gathering up medicines and
chemicals.

Taking advantage of having Cynthia's attention now, Mr. Ages started telling
her what they were going to do.

"Cynthia dear, would you like to go visit Justin? Would you like him to
show you all of Thorn Valley while he carries you?" When he put it this
way, it was impossible for Cynthia to say no.

"Yes Mr. Ages! Of course I'd like it!!" Her eyes glowed with this
proposition. She'd always wanted to explore a place outside of the farm, and
this opportunity couldn't go to waste, "I'd like to go! When do we
leave?"

Even the question was pigheaded.

"Well, in that case.. How 'bout right now!?" Mr. Ages had convinced
her, something he'd never imagined he could do, and he felt as if he'd
successfully performed one of the most difficult tasks of his life. Of course
something like this had to happen to get him to say exactly the right words at
the right time.

Martin had packed up nearly everything they needed. It wasn't at all heavy.
Martin could easily carry it all. "Mr. Ages, I should go back to pack up
my own stuff." Mr. Ages left Cynthia on the floor and got ready
to leave. "Where should we all meet?"

"At the shores of the river, but don't worry, I know your mother and I
know that she has packed all your essential things... By the way, none of you
have drank any water from the river, have you?" This question made Mr.
Ages shudder with the fear that the children might answer 'yes'.

"No.", said Martin, "You've told us that the water sometimes has
those little... critters, what's that word you always call them?" Mr. Ages
breathed a sigh of relief. "Germs, Martin. And I'm glad to hear that none
of us has had a drink from that river, because the river water is
contaminated."

"What does 'contaminated' mean, Mr. Ages?," Cynthia asked. Like
always, she was fidgeting when she shouldn't.

"Dear, 'contaminated' means..." he searched for the right words while
he picked her up and sat her on a stool. "...look at it this way. When
your mother brings home a fruit and you want to eat it right then and there,
she tells you that you should wash it first, because that fruit was in the
dust, sand, or dirt, and you could get sick eating it dirty like that. Do you
understand?" Mr. Ages hoped that Cynthia had understood.

"No, Mr. Ages, I do what my mommy tells me, but I never heard her say that
word before." Mr. Ages was crestfallen at hearing this and felt ashamed
because he couldn't get across to her what he wanted to say.

"Well Cynthia, I'll explain it to you later. Now, let's go!!" Mr.
Ages set Cynthia down and took her by the hand, hastening her. He spoke to
Martin, "Hurry Martin, let's not waste time."

Suddenly, Cynthia began to look a little pale.

"Mr. Ages...? I don't feel so good..." Cynthia put her little paw to
her head.

Mr. Ages stopped cold. So did Martin. Mr. Ages feared the worst..

"What do you mean you don't feel good, dear?" Mr. Ages felt his blood
run like ice, waiting for the answer. Martin went in turn deathly pale.
"What do you feel?"

"It hurts here," she pointed to her head, "It hurts."

"Does it hurt a lot?" Mr. Ages put his paw to her head to feel if she
had a fever. He couldn't believe it.

"Yes," said Cynthia, "it feels like my head is going 'bump,
bump'..." Mr. Ages quickly signaled for Martin to come.

"Martin, hand me the vial with the blue powder in it. I think Cynthia
really doesn't feel good." Martin urged his hands, nervous and trembling,
to pick up the vial. He knew that if anyone could cure his little sister,
it was Mr. Ages.

"Martin," said Mr. Ages, "on your way here to the laboratory,
did you go by the river?"

Martin nodded.

"That's all I needed to know." Mr. Ages took a small portion of the
blue powder. "Dear," Mr. Ages spoke softly to Cynthia,"Please, I
want you to stick out your tongue at me." Cynthia looked at Mr. Ages with
a beaming look, thinking Mr. Ages was playing a game with her.

She said, "Like this?" And stuck out her tongue.

"Very good, my dear, now stay like that for a little while longer..."
Mr. Ages put a little of the blue powder on Cynthia's tongue and almost
instantly, her tongue turned a dark purple color. Mr. Ages shut his eyes,
squeezing his eyelids as he'd confirmed his darkest suspicions. Martin was
anxious.

"Martin, give me the white, liquid medicine." The boy hastened to
bring it to him. "Cynthia, I want you to drink this." He poured the
medicine into a small cup he had close by and gave it to her to drink.

"Yuck!!, It tastes icky!," yelled Cynthia, making a face.

"Pretend it's breakfast milk, Cynthia!" Martin tried to get her
attention so she wouldn't spit out the medicine.

Cynthia did as she was told and shut her eyes, thinking about breakfast time,
bringing from her memory the exquisite scent of warm cheese and of the warm
milk her mother gave her every morning, and that way, she got the medicine down
her throat.

Shortly after, she felt much better.

"Mr. Ages! My head doesn't hurt anymore! I feel a lot better!!" Mr.
Ages felt even more relieved than Cynthia.

"Martin, it would be a good idea if all of us took some medicine now, to
avoid any problems along the way. It's a rather long road and we have to get
there as fast as we can. Ah! Let's not forget to take some food. I
have purified some water for the trip."

"Will it be enough for everyone, Mr.Ages?" Martin's question seemed
very timely. It made Mr. Ages think about how they were all going to survive
until they got to Thorn Valley, taking all their essential belongings, and the
food and water for the trip. In a moment, Mr. Ages realized that the water he
was carrying would not be enough for all of them.

"I think not, but I know your mother and I know that she'll also be
bringing enough water for all of you." The three of them got together at
the door,"I think the laboratory might have to stay closed for a long
time."

"What do you mean Mr. Ages?" Martin was a bit worried, "What
will happen to everything?" Mr. Ages looked kindly at him and told him his
plan.

"I don't think we'll have to stay away for too long. What I'm going to do
is prepare more medicine for all the animals and pour it into the brook so that
it'll nullify the effect of the poison that's already in the water;
that will make it pure again. When the danger has passed, we'll come back and
continue our normal life. That will be simple, won't it?"

The boy looked at him, appearing not to have understood the plan very well. Mr.
Ages shrugged and continued. "I don't think you understood me, but it
doesn't matter, you'll understand soon enough. Come on Cynthia, let's hurry up
and get out of here!!"

This said, the three left the laboratory, carrying the provisions and the
medicines, while they listened to the profound echo of the door closing behind
them with a pang of sadness, and Cynthia even waving goodbye to the laboratory.
They then hurried to get into the basket that would take them to the surface.