 Tarzan and the Diamond of Arshere. Tarzan is leading an expedition organized to search for Brian Gregory in the Belgian Congo. Among the party are Gregory's father and sister. Following them are Atan Tom and Lal Tosk, who are determined to get possession of a map showing the location of Arshere. They believe Tarzan has this map. In camp on the banks of the tributary of the Ubangi River, Tarzan kills a crocodile in defense of Larsen. Wolf secures a sleeping potion from the native witch doctor and puts it into Gregory's canteen. Magra exchanges Wolf's water bag for Gregory's. Next morning, Larsen comes from his tent and calls to Tarzan. Tarzan! Yes, Larsen, what is it? Something been wrong with the Dutchman. Something wrong? What do you mean? He's asleep. He can't wake him up. You can't wake him up? He's sure. He's generally the first one up in the morning. Now he's been sleeping like a buffalo and they can't wake him up. Oh, no, no! Wait, Tarzan! He seemed to be all right last night, Larsen. Yes, sure. He was sound asleep when it turned in. What is it, Tarzan? Wolf. Larsen says he can't wake him up. I'll have a look at him as to what's wrong. Come on. I'll touch a fever, perhaps, and maybe too much kidneys. A little fever couldn't knock that fella out. He's been in the jungle too long. Look, there he is and his cut sped out like a wet blanket. He did not remove his clothing last night, eh? He sure been there through the world. Wolf. Wolf. Wake up, Tarzan. Let me have a look at him. You see, his eyes look as if he had taken something to make him sleep. Oh, Larsen, go to the cook tent and bring me some vinegar or a lemon, eh? Yeah, sure, Lieutenant. This looks like a cottage of some kind, Tarzan. Canine doesn't act that way. But it do. It is something much stronger. A different action entirely. Yeah, be in the vinegar, Lieutenant. I'll see, Larsen. Now, that canteen and the tin cup. Yeah, sure. Then, if I could get my arm under here. That water isn't clear, Dono. Yeah, let me taste it. Here, you try it. Tell me what you think. Sakai, that fool has been drinking native mbanchai. And it's strong. So that's it, eh? No wonder I couldn't make him up. Give me your canteen, Larsen, and empty this one, eh? Yeah, sure. Now, we can get this down his throat. Here, I'll lift him up. No, I cannot get these jaws apart. Wait a minute. I'll pry them apart with my knife blade. Ow. That pain froth on his mouth, Lieutenant. Yes, yes, the vinegar counteracts the narcotic. Now, once more, Tarzan, a little more. Ah, so. Now, Larsen, we will get him on his feet and walk him around outside. Let me handle him, Dono. No, no, no. You go back to the others and explain matters. We will have him in good shape in no time. Come, Larsen. Yes, sure. What's the trouble, Larsen? Wolf's sick. Nothing serious, Gregory. Anything I can do? No, we'll take care of him. Let me have him, Dono. I'll walk him around. You go with Gregory. I'll keep him walking, and he will come out of it presently. Come, Mr. Gregory, our friend worked him through. What's the matter, Dad? What's wrong with Wolf? Tarzan and Dono say it's nothing serious. Oh, vraiment, vraiment, Memeuselelein. You will be all right in a few moments. Do not worry yourself. Perhaps only I taught you fever, no? No, Memeuselelein. Fever does not affect one in that way. He ate something last night which did not agree with him. Perhaps drank something routine in Dono, huh? But we all ate and drank the same thing. And you all feel well this morning? Personally, I never felt better. And I, Mr. Gregory. Hey, who, Memeuselein? No, I'm fine. Can't they're always agrees with me? Wolf seems to be coming out of it nicely. He's walking along with Tarzan and looking like a drum major. I'm certainly glad it was nothing serious. How is it, Tarzan? We've got him awake. He'll be all right now. The judgment sure was in a bad fix. He ain't got to forget, neither. How is it now? I'm all right. He is heady, that's all. Was anyone else down? No one. Wolf, did you eat or drink anything last night that did not sit well with you? Nothing. Only what everyone else had. How do you feel here correctly? Me? Fine. I was just telling Dono I never felt better. That's funny. I had an experience once something like this a long time ago. I ate some bad elephant meat. Bad elephant meat? Oh, that must have been terrible. Well, it was, Margaret. I was pretty sick. Saw things like Sabre the lioness climbing up into the trees after me and hiss to the snake. I've never since eaten elephant meat. May, may, my view, we are going to get out of the way soon, no? It is late. No, we'll stay and come today. Give Wolf's head a chance to clear. All right, Gregory? Of course. A day or two won't make any difference. I'll be glad for the rest. No, I'd like it myself. It'll give me a chance to do some very necessary men. You know, these jungle trails are terribly hard on clothes. That is a good idea, Helen. Might be also in rags. Well, let the natives know, Larson, that we don't move until morning. Yeah, sure. They won't be sorry. But I'm all right, Tarzan. Just a little, heasy. No, we'll rest today. You take it easy. Me, it is so hot. You know, I wouldn't enjoy a dip in that river. We may not have another opportunity for a long time. After Mr. Larson's experience of last night? Oh, I will stay as far from the river as possible. A dip in that river, Lieutenant? Oh, no, thank you. Why the nest of crocodiles? Come on, Margaret, we'll do our housework. And now, Dad, you keep away from the water. Hmm. The swim sounds interesting, Dono. But I don't know. Crocodiles. Do you think it's safe? I don't think so, Tarzan. Do we risk it? Why not? I'll watch Gimli and his brothers. They won't bother you. The early rays of the sun splinter the grey waters of the river into silver spikes, as Tarzan, Dono, and Gregory slip off a plunge in its cool depths. Larson, after relaying Tarzan's orders to the natives, follows the three men, and despite his experience of the night before, joins them on the rank. He starts unlacing his heavy shoes. You're certainly not going in, Larson. Yeah, sure I am. Why not? After last night? Oh, Dad. All in the day's work, Mr. Gregory. If a fellow stopped doing things in the jungle every time he got in the bed fixed, he would have to stay in the tent all day. Well, if you've got the nerve, you can't scare me. I'm going in too. Wolf sprawls on a blanket in the shade of a tree not far from where Helen and Magra, seated before their own canvas shelter, are busy with their mending. Hand me that spool of thread, will you please? You know it's absolutely uncanny the way Tarzan slips through bushes simply bristling with thorns without even so much as a single scratch. He glides through apparently solid walls of underbrush without even disturbing a tweak. A passage seems to open before him as if by magic. Oh, he's wonderful, Helen. Yes, he's pretty much of a... Why, Magra? Why, this forest guard of ours seems to have made quite an impression on you. Oh, no. No, I am only interested in... He's interested in nothing. Magra, you're in love with him. It's in your eyes. Oh, Helen, no. No, it is only that I am interested in him as a studying human nature. Oh, Earth's noblest thing, a man perfected. But seriously, Helen, not before last I suggested to you that you give your maps to Tarzan to keep for you. You have not done so. Oh, the excitement of last night, Tarzan killing that crocodile drove it completely out of my mind. I'll give it to him, though, at the first opportunity. But can't you tell me why? Not now, perhaps later. But you will do so today, just as soon as we're all together again. Yes, Magra. Sprawled on his blanket, the sullen wolf tries to figure out how he got the sleeping potion meant for Gregor the night before. He realizes he's been tricked. But how? By whom? No one was aware of his meeting with the witch doctor nor of its significance. At the thought of the native medicine man, wolf climbs to his feet and goes to his tent to reappear with the black snake whip grasped in his hand, then keeping his own tent between himself and the two young women, he makes his way quickly to the ragged shelter of the witch doctor. He enters unceremoniously. Meanwhile, Tarzan, Dono, Larson, and Gregory have returned from their bathing and have found Helman, Magra, busily engaged in their sewing. How's the sewing circle progressing, ladies? Oh, fine, Dad. I've just finished one of your shirts here. Look it over. Before I started to work on it, it looked as though you'd crawl through a whole mile of barbed wire entanglements. You think I got to take a look at Wolf? He certainly got hold of something that put him out. He was stretched on that blanket over there beside his tent a few moments ago. I thought he was asleep. I saw him go to the native quarters. He was carrying his whip. I think I'll take a turn to camp. I won't belong. You tell me, you ugly who got that stuff from you last night, or I'll drag it out of you with this whip. Then it was you, you black devil. You put that rotten stuff in my canteen. A couple of good cuts with the black snake will do you good. Now, a very worthy speaker. All right, then. Maybe this will bring it out. No, no, no whip. Only no savvy negotiation. Come on, speak up. This is the only way to handle you savages. Wolf raises the heavy black snake for another blow. Suddenly, his arm is caught from behind in a grip. Like a helpless child, he spun around to look into the grim cold eyes of Tarzan.