| sleuth(noun, information, plant, watch, investigate) |
| scout(noun, verb, person, plant, watch) |
| snooper(noun, agent, hound, sneak) |
| emissary(noun, plant, watch, agent) |
| operative(noun, plant, agent, mole) |
| patrol(noun, person, force, plant, bear) |
| guard(noun, watch, lookout, patrol) |
| lookout(noun, plant, watch, guard, agent) |
| mole(noun, plant, watch, agent) |
| picket(noun, plant, watch, guard, agent) |
| runner(noun, watch, guard, lookout) |
| spotter(noun, plant, watch, guard, agent) |
| undercover agent(noun, expression, plant, watch, agent) |
| watch(guard, lookout, custodian, warden) |
| advance(noun, watch, guard, lookout) |
| adventurer(noun, watch, guard, lookout) |
| escort(noun, watch, guard, lookout) |
| guide(watch, lookout) |
| infiltrator(noun, plant, mole) |
| investigating(noun, watch, guard, lookout) |