Two drug couriers were caught with £6.8m of heroin as they travelled back to Scotland from the Midlands.
Martin Lauder, 29, and David McShane, 28, were stopped by police in a hired Vauxhall Insignia on the M74 near Lesmahagow, South Lanarkshire.
Police seized two bags from the car which held 60 taped packages of heroin.
They admitted being concerned in the supply of the class A drug at the High Court in Glasgow.
Prosecutor Shanti Maguire said police got a tip off the pair were going to England to "uplift a large quantity of controlled drugs"
The men were then traced to the Hilton Ricoh Arena Hotel in Coventry. Police planned to stop their car as they headed back to Scotland.
Lauder, of Bearsden, and McShane, of Maryhill, made no comment after they were stopped on the M74 on 12 July this year.
The heroin had a purity of up to 61% and could be adulterated to 157kg.
Miss Maguire told the court police "intelligence suggests" the pair were acting as "couriers".
Lauder's lawyer Graeme Brown and Mark Moir, defending McShane, will give mitigation at the next calling of the case.
The two were remanded in custody.
Lady Dorrian deferred sentencing until 10 December in Edinburgh.