The Tall Man

The tall man works his way over the soft, sandy, desert soil. He uses alien provided devices something like very short skis. The ski like devices are coated with some sort of very low friction compound. The stuff should last long enough to get him to the base and not too much longer. It's the best that his alien employers can do on short notice. While the little skis allow him to slide over the soft sand, they still require considerable effort from the tall man. However, the tall man's physical conditioning is up to the demands of the job.
The tall man carries devices in his backpack that are entirely capable of nullifying normal surveillance devices and might allow the tall man to move undetected into and within the military base. The risk is that the base is protected by alien devices which can detect the tall man, despite his own anti-surveillance gear. If the terrorists find him early, he's dead or worse.
The tall man is near exhaustion when he finally reaches the terrorist base. He rests briefly in the shadow of a small fold in the sea of sand which surrounds the base. There's no sign that he has been detected. Then again, if those inside have detected him, perhaps they will just wait for the tall man to enter their trap, rather than risk his escape back into the desert.
There are four guards inside the fence, one at each corner of the rectangular enclosure. There's, per the tall man’s map, an entrance/exit gate on the far side of the compound. There will normally be two guards inside a cement block guard shack, at the entrance/exit gate. They'll have TV cameras which view the whole of the enclosure. If the cameras are advanced alien devices, the tall man will be discovered and die. That is, he'll just die if he's lucky.
There's a light! A small red light. Perhaps it's a security device? The tall man detects a sweetish, stale odor. A wolfish grin briefly crosses his face. A guard is enjoying a little marijuana, or kif as it's called locally. From the intensity of the stench, it's very strong stuff. In fact, it'll prove deathly strong to the user.
The tall man carefully retrieves several thin pieces of pipe from within his night suit. Assembled, they form a very serviceable blow gun. The tall man squirms silently across the desert sand. The guard hears only a whisper of air, then the tiny dart with its alien poison bites into his cheek. The guard slumps forward, but doesn't collapse. Apparently, his rifle has wedged into the sand and it's holding him up! It's incredibly good luck for the tall man.
The next step is for the tall man to get inside the compound. The process is simple, just very risky. The aliens have provided the tall man with a small anti-gravity device. The little item will work just once and only for a very short time. If the base has a full alien security system, it'll detect the maximum overload death throes of the alien device. However, if he's able to fly over the fence and isn't detected, the tall man will have increased his chances of survival to perhaps even odds.
The tall man triggers the anti-gravity device and it lifts him over the outer fence and deposits him in the shadows near the main building. The way-too-small device gives up with the tall man still some half dozen feet above the ground. However, the tall man rolls on landing and survives uninjured.
There's no point in waiting to see if he's been discovered. There's no way out of the compound for the tall man, while the men inside the base are still alive. From here on, The tall man will either succeed or die!
The tall man is almost invisible in his night suit, in the darkness. He pulls metal steps from his backpack. The steps have some sort of super adhesive on the base of each step. Once the cover is pulled off, he has a few seconds to place the step against some sort of surface to which the adhesive will bond.